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question:The function ( F(x) = left| cos^2 x + 2 sin x cos x - sin^2 x + Ax + B right| ) on ( 0 leq x leq frac{3}{2} pi ) attains a maximum value ( M ) that depends on parameters ( A ) and ( B ). For which values of ( A ) and ( B ) is ( M ) minimized? Prove your conclusion.
answer:Okay, so I have this problem where I need to find the values of A and B that minimize the maximum value M of the function F(x) on the interval from 0 to 3π/2. The function is given as F(x) = |cos²x + 2 sinx cosx - sin²x + Ax + B|. First, I need to understand what this function looks like. The expression inside the absolute value seems to involve trigonometric functions and linear terms in x. Maybe I can simplify the trigonometric part first. I remember that cos²x - sin²x is equal to cos(2x), and 2 sinx cosx is sin(2x). So, substituting these identities, the expression becomes cos(2x) + sin(2x). That simplifies things a bit. So now, F(x) = |cos(2x) + sin(2x) + Ax + B|.Hmm, cos(2x) + sin(2x) can be written as a single sine or cosine function with a phase shift. I think it's something like sqrt(2) sin(2x + π/4). Let me verify that. Yes, using the identity a sinθ + b cosθ = sqrt(a² + b²) sin(θ + φ), where φ = arctan(b/a). In this case, a = 1 and b = 1, so sqrt(1 + 1) = sqrt(2), and φ = arctan(1/1) = π/4. So, cos(2x) + sin(2x) = sqrt(2) sin(2x + π/4). So, F(x) = |sqrt(2) sin(2x + π/4) + Ax + B|. Now, I need to find A and B such that the maximum value of this function over [0, 3π/2] is minimized.I think this is related to minimizing the maximum deviation, which might involve some kind of least squares or maybe Chebyshev approximation. But I'm not entirely sure. Maybe I should first analyze the function without the absolute value and see how it behaves.Let me define G(x) = sqrt(2) sin(2x + π/4) + Ax + B. Then F(x) = |G(x)|. The maximum of F(x) is the maximum of |G(x)| over the interval. To minimize this maximum, I need to choose A and B such that G(x) oscillates as little as possible around zero, right? Because if G(x) is close to zero everywhere, then |G(x)| will be small everywhere, and the maximum will be minimized.So, maybe I need to make G(x) as flat as possible, meaning its derivative should be zero or something. Let me think about the derivative. The derivative of G(x) is G'(x) = 2 sqrt(2) cos(2x + π/4) + A. If I set this derivative to zero, I can find critical points.But wait, if I set G'(x) = 0, that would give me points where the function G(x) has local maxima or minima. Maybe I can use these points to adjust A and B so that the function G(x) has equal maxima and minima, which would make the maximum of |G(x)| as small as possible.Alternatively, perhaps I should consider the function G(x) and try to fit a straight line Ax + B to the curve sqrt(2) sin(2x + π/4) such that the maximum deviation is minimized. This sounds like an optimization problem where I want to minimize the maximum error, which is similar to Chebyshev approximation.In Chebyshev approximation, the optimal linear approximation minimizes the maximum deviation, and the error function has equal ripples, meaning it attains its maximum absolute value at several points with alternating signs. So, maybe I need to adjust A and B such that G(x) has equal maxima and minima at certain points in the interval.Let me try to find points where G(x) reaches its maximum and minimum. Since G(x) is a combination of a sine wave and a linear function, the extrema will occur where the derivative is zero, i.e., where 2 sqrt(2) cos(2x + π/4) + A = 0. So, cos(2x + π/4) = -A / (2 sqrt(2)). For this equation to have solutions, the right-hand side must be between -1 and 1. Therefore, |A| / (2 sqrt(2)) ≤ 1, which implies |A| ≤ 2 sqrt(2). If |A| > 2 sqrt(2), then G'(x) never zero, meaning G(x) is either always increasing or always decreasing. In that case, the maximum of |G(x)| would occur at the endpoints of the interval. But since we want to minimize the maximum, it's better to have A such that G'(x) has solutions, so that G(x) has local maxima and minima.Assuming |A| ≤ 2 sqrt(2), then there are points where G'(x) = 0. Let's denote these points as x1, x2, etc. At these points, G(x) will have local maxima or minima.To minimize the maximum of |G(x)|, we need to adjust A and B such that the maximum and minimum values of G(x) are equal in magnitude but opposite in sign. That way, the maximum absolute value is minimized.So, let's suppose that at some points x1 and x2, G(x1) = M and G(x2) = -M. Then, the maximum |G(x)| would be M, and we need to find A and B such that M is as small as possible.To find such A and B, we can set up equations based on the critical points. Let's say x1 and x2 are two points where G(x1) = M and G(x2) = -M, and G'(x1) = G'(x2) = 0.So, we have:1. G(x1) = sqrt(2) sin(2x1 + π/4) + A x1 + B = M2. G(x2) = sqrt(2) sin(2x2 + π/4) + A x2 + B = -M3. G'(x1) = 2 sqrt(2) cos(2x1 + π/4) + A = 04. G'(x2) = 2 sqrt(2) cos(2x2 + π/4) + A = 0From equations 3 and 4, we get:cos(2x1 + π/4) = -A / (2 sqrt(2))cos(2x2 + π/4) = -A / (2 sqrt(2))This implies that 2x1 + π/4 and 2x2 + π/4 are either equal or supplementary angles, because cosine is equal for angles that are supplementary.So, either 2x2 + π/4 = 2x1 + π/4 + 2π k, which would mean x2 = x1 + π k, or 2x2 + π/4 = - (2x1 + π/4) + 2π k.The first case would mean x2 = x1 + π k, but since x is in [0, 3π/2], k can be 0 or 1. Let's see if that's possible.If k=0, x2 = x1, which is trivial and doesn't give us a new point. If k=1, x2 = x1 + π. But since x1 is in [0, 3π/2], x2 would be in [π, 5π/2], but our interval is up to 3π/2, so x2 would be in [π, 3π/2]. So, it's possible.The second case: 2x2 + π/4 = - (2x1 + π/4) + 2π k.Solving for x2:2x2 = -2x1 - π/2 + 2π kx2 = -x1 - π/4 + π kSince x2 must be in [0, 3π/2], let's see what k can be.If k=1:x2 = -x1 - π/4 + π = π - x1 - π/4 = (3π/4) - x1So, x2 = 3π/4 - x1This is a valid expression because if x1 is in [0, 3π/2], then x2 would be in [-3π/4, 3π/4], but since x2 must be ≥ 0, x1 must be ≤ 3π/4.So, x2 = 3π/4 - x1Therefore, we have two possibilities for x2: either x2 = x1 + π or x2 = 3π/4 - x1.Let's consider the second case first because it might give us a more symmetric solution.So, if x2 = 3π/4 - x1, then we can write:From equations 1 and 2:sqrt(2) sin(2x1 + π/4) + A x1 + B = Msqrt(2) sin(2x2 + π/4) + A x2 + B = -MSubstituting x2 = 3π/4 - x1:sqrt(2) sin(2*(3π/4 - x1) + π/4) + A*(3π/4 - x1) + B = -MSimplify the argument of sine:2*(3π/4 - x1) + π/4 = 3π/2 - 2x1 + π/4 = (3π/2 + π/4) - 2x1 = (7π/4) - 2x1So, sin(7π/4 - 2x1) = sin(7π/4) cos(2x1) - cos(7π/4) sin(2x1) = (-sqrt(2)/2) cos(2x1) - (sqrt(2)/2) sin(2x1) = -sqrt(2)/2 (cos(2x1) + sin(2x1))But wait, let's compute sin(7π/4 - 2x1):sin(7π/4 - 2x1) = sin(7π/4) cos(2x1) - cos(7π/4) sin(2x1) = (-sqrt(2)/2) cos(2x1) - (sqrt(2)/2) sin(2x1) = -sqrt(2)/2 (cos(2x1) + sin(2x1))But from earlier, we have that cos(2x1 + π/4) = -A / (2 sqrt(2)). Let's denote θ = 2x1 + π/4, so cosθ = -A / (2 sqrt(2)). Then, sinθ = sqrt(1 - cos²θ) = sqrt(1 - A²/(8)).But θ = 2x1 + π/4, so 2x1 = θ - π/4, and x1 = (θ - π/4)/2.Similarly, sin(2x1) = sin(θ - π/4) = sinθ cos(π/4) - cosθ sin(π/4) = (sinθ - cosθ)/sqrt(2)Similarly, cos(2x1) = cos(θ - π/4) = cosθ cos(π/4) + sinθ sin(π/4) = (cosθ + sinθ)/sqrt(2)So, sin(7π/4 - 2x1) = -sqrt(2)/2 (cos(2x1) + sin(2x1)) = -sqrt(2)/2 * [ (cosθ + sinθ)/sqrt(2) + (sinθ - cosθ)/sqrt(2) ] = -sqrt(2)/2 * [ (cosθ + sinθ + sinθ - cosθ)/sqrt(2) ] = -sqrt(2)/2 * [ 2 sinθ / sqrt(2) ] = -sqrt(2)/2 * sqrt(2) sinθ = -sinθTherefore, sin(7π/4 - 2x1) = -sinθ = -sin(2x1 + π/4)So, going back to the equation:sqrt(2) sin(7π/4 - 2x1) + A*(3π/4 - x1) + B = -MWhich becomes:sqrt(2)*(-sinθ) + A*(3π/4 - x1) + B = -MBut from equation 1:sqrt(2) sinθ + A x1 + B = MSo, we have:sqrt(2)*(-sinθ) + A*(3π/4 - x1) + B = -Msqrt(2) sinθ + A x1 + B = MLet me write these two equations:1. sqrt(2) sinθ + A x1 + B = M2. -sqrt(2) sinθ + A*(3π/4 - x1) + B = -MLet me add these two equations:[sqrt(2) sinθ - sqrt(2) sinθ] + [A x1 + A*(3π/4 - x1)] + [B + B] = M - MSimplifying:0 + A*(3π/4) + 2B = 0So, (3π/4) A + 2B = 0Therefore, B = - (3π/8) ANow, subtract equation 2 from equation 1:[sqrt(2) sinθ + sqrt(2) sinθ] + [A x1 - A*(3π/4 - x1)] + [B - B] = M + MSimplifying:2 sqrt(2) sinθ + A*(2x1 - 3π/4) = 2MBut from equation 3, we have:2 sqrt(2) cosθ + A = 0 => A = -2 sqrt(2) cosθSo, substituting A into the equation:2 sqrt(2) sinθ + (-2 sqrt(2) cosθ)*(2x1 - 3π/4) = 2MLet me factor out 2 sqrt(2):2 sqrt(2) [ sinθ - cosθ*(2x1 - 3π/4) ] = 2MDivide both sides by 2:sqrt(2) [ sinθ - cosθ*(2x1 - 3π/4) ] = MBut θ = 2x1 + π/4, so 2x1 = θ - π/4, so 2x1 - 3π/4 = θ - π/4 - 3π/4 = θ - πTherefore:sqrt(2) [ sinθ - cosθ*(θ - π) ] = MHmm, this seems complicated. Maybe I should express everything in terms of θ.We have:A = -2 sqrt(2) cosθFrom earlier, B = - (3π/8) A = - (3π/8)*(-2 sqrt(2) cosθ) = (3π/4) sqrt(2) cosθSo, B = (3π/4) sqrt(2) cosθNow, let's go back to equation 1:sqrt(2) sinθ + A x1 + B = MSubstitute A and B:sqrt(2) sinθ + (-2 sqrt(2) cosθ) x1 + (3π/4) sqrt(2) cosθ = MFactor out sqrt(2):sqrt(2) [ sinθ - 2 cosθ x1 + (3π/4) cosθ ] = MBut x1 = (θ - π/4)/2, so:sqrt(2) [ sinθ - 2 cosθ*(θ - π/4)/2 + (3π/4) cosθ ] = MSimplify:sqrt(2) [ sinθ - cosθ*(θ - π/4) + (3π/4) cosθ ] = MDistribute the cosθ:sqrt(2) [ sinθ - θ cosθ + (π/4) cosθ + (3π/4) cosθ ] = MCombine like terms:sqrt(2) [ sinθ - θ cosθ + (π/4 + 3π/4) cosθ ] = Msqrt(2) [ sinθ - θ cosθ + π cosθ ] = MFactor out cosθ:sqrt(2) [ sinθ + cosθ (π - θ) ] = MSo, we have:M = sqrt(2) [ sinθ + cosθ (π - θ) ]But we also have from equation 3:A = -2 sqrt(2) cosθAnd from equation 4:B = (3π/4) sqrt(2) cosθSo, M is expressed in terms of θ. Now, we need to find θ such that M is minimized.Wait, but θ is related to x1, which is in [0, 3π/2]. So, θ = 2x1 + π/4, so θ ranges from π/4 to 2*(3π/2) + π/4 = 3π + π/4 = 13π/4.But since sine and cosine are periodic with period 2π, we can consider θ in [π/4, 13π/4], but effectively, we can look for θ in [π/4, 9π/4] because beyond that, it's just repeating.But this seems quite involved. Maybe there's a simpler approach.Alternatively, perhaps I can consider the function G(x) = sqrt(2) sin(2x + π/4) + Ax + B and try to make it as flat as possible. That is, choose A and B such that the function G(x) has equal maxima and minima, which would minimize the maximum absolute value.To do this, I can set up the function so that at the points where G'(x) = 0, the function G(x) has equal absolute values but opposite signs. This is similar to the equioscillation theorem in approximation theory, where the best approximation equioscillates between its extreme values.So, let's assume that there are at least two points x1 and x2 in [0, 3π/2] where G(x1) = M and G(x2) = -M, and G'(x1) = G'(x2) = 0.From earlier, we have:G'(x) = 2 sqrt(2) cos(2x + π/4) + A = 0So, cos(2x + π/4) = -A / (2 sqrt(2))Let me denote φ = 2x + π/4, so cosφ = -A / (2 sqrt(2))Therefore, φ = arccos(-A / (2 sqrt(2))) or φ = -arccos(-A / (2 sqrt(2))) + 2π kBut since φ = 2x + π/4, we can write:x = (φ - π/4)/2So, the critical points are at x = (arccos(-A / (2 sqrt(2))) - π/4)/2 and x = (-arccos(-A / (2 sqrt(2))) + π/4)/2 + π kBut we need to find x in [0, 3π/2]. Let's focus on the principal values.Let me denote α = arccos(-A / (2 sqrt(2))). Then, the critical points are:x1 = (α - π/4)/2x2 = (-α - π/4)/2 + πWait, because cosφ = -A / (2 sqrt(2)) has solutions at φ = α and φ = -α + 2π, so:For φ = α: x1 = (α - π/4)/2For φ = -α + 2π: x2 = (-α + 2π - π/4)/2 = (-α + 7π/4)/2But we need x2 to be in [0, 3π/2]. Let's check:x2 = (-α + 7π/4)/2Since α = arccos(-A / (2 sqrt(2))), and arccos returns values in [0, π], so α is in [0, π]. Therefore, -α is in [-π, 0], so -α + 7π/4 is in [7π/4 - π, 7π/4] = [3π/4, 7π/4]. Dividing by 2, x2 is in [3π/8, 7π/8].But 7π/8 is less than 3π/2, so x2 is within the interval.So, we have two critical points: x1 and x2.At these points, G(x1) = M and G(x2) = -M.So, let's write the equations:1. G(x1) = sqrt(2) sin(2x1 + π/4) + A x1 + B = M2. G(x2) = sqrt(2) sin(2x2 + π/4) + A x2 + B = -MAlso, from G'(x1) = 0:3. 2 sqrt(2) cos(2x1 + π/4) + A = 0 => cosφ1 = -A / (2 sqrt(2)) where φ1 = 2x1 + π/4 = αSimilarly, for x2:4. 2 sqrt(2) cos(2x2 + π/4) + A = 0 => cosφ2 = -A / (2 sqrt(2)) where φ2 = 2x2 + π/4 = -α + 2πBut sinφ2 = sin(-α + 2π) = sin(-α) = -sinαSo, sin(2x2 + π/4) = sinφ2 = -sinαSimilarly, sin(2x1 + π/4) = sinαSo, equations 1 and 2 become:1. sqrt(2) sinα + A x1 + B = M2. sqrt(2) (-sinα) + A x2 + B = -MLet me write these as:1. sqrt(2) sinα + A x1 + B = M2. -sqrt(2) sinα + A x2 + B = -MNow, let's add these two equations:[sqrt(2) sinα - sqrt(2) sinα] + A(x1 + x2) + 2B = M - MSimplifying:0 + A(x1 + x2) + 2B = 0 => A(x1 + x2) + 2B = 0From earlier, we have:x1 = (α - π/4)/2x2 = (-α + 7π/4)/2So, x1 + x2 = [ (α - π/4) + (-α + 7π/4) ] / 2 = (6π/4)/2 = (3π/2)/2 = 3π/4Therefore, A*(3π/4) + 2B = 0 => B = - (3π/8) ANow, subtract equation 2 from equation 1:[sqrt(2) sinα + sqrt(2) sinα] + A(x1 - x2) + [B - B] = M + MSimplifying:2 sqrt(2) sinα + A(x1 - x2) = 2MCompute x1 - x2:x1 - x2 = [ (α - π/4)/2 ] - [ (-α + 7π/4)/2 ] = [α - π/4 + α - 7π/4]/2 = [2α - 8π/4]/2 = [2α - 2π]/2 = α - πSo, x1 - x2 = α - πTherefore, the equation becomes:2 sqrt(2) sinα + A(α - π) = 2MBut from equation 3, we have:A = -2 sqrt(2) cosαSo, substituting A:2 sqrt(2) sinα + (-2 sqrt(2) cosα)(α - π) = 2MFactor out 2 sqrt(2):2 sqrt(2) [ sinα - cosα (α - π) ] = 2MDivide both sides by 2:sqrt(2) [ sinα - cosα (α - π) ] = MSo, M = sqrt(2) [ sinα - cosα (α - π) ]Now, we need to find α such that M is minimized. Since M is expressed in terms of α, we can take the derivative of M with respect to α and set it to zero to find the minimum.Let me denote:M(α) = sqrt(2) [ sinα - cosα (α - π) ]Compute dM/dα:dM/dα = sqrt(2) [ cosα - [ -sinα (α - π) + cosα * 1 ] ] = sqrt(2) [ cosα + sinα (α - π) - cosα ] = sqrt(2) [ sinα (α - π) ]Set dM/dα = 0:sqrt(2) sinα (α - π) = 0So, either sinα = 0 or α - π = 0Case 1: sinα = 0 => α = 0, π, 2π, etc.But α = arccos(-A / (2 sqrt(2))) and arccos returns values in [0, π], so α ∈ [0, π]. So, possible α = 0 or α = π.Case 2: α - π = 0 => α = πSo, the critical points are at α = 0 and α = π.Let's evaluate M at these points.First, α = 0:M(0) = sqrt(2) [ sin0 - cos0 (0 - π) ] = sqrt(2) [ 0 - 1*(-π) ] = sqrt(2) πSimilarly, α = π:M(π) = sqrt(2) [ sinπ - cosπ (π - π) ] = sqrt(2) [ 0 - (-1)(0) ] = 0Wait, M(π) = 0? That can't be right because M is the maximum of |G(x)|, which can't be zero unless G(x) is identically zero, which would require A and B to be such that sqrt(2) sin(2x + π/4) + Ax + B = 0 for all x, which is impossible because the sine function is oscillatory and the linear term would dominate.So, perhaps α = π is not a valid solution because it leads to M = 0, which is not possible. Therefore, the only valid critical point is α = 0.But let's check what happens when α = 0.If α = 0, then cosα = 1, so from A = -2 sqrt(2) cosα = -2 sqrt(2)*1 = -2 sqrt(2)And B = - (3π/8) A = - (3π/8)*(-2 sqrt(2)) = (3π/4) sqrt(2)So, A = -2 sqrt(2), B = (3π/4) sqrt(2)Now, let's compute M(0):M(0) = sqrt(2) [ sin0 - cos0 (0 - π) ] = sqrt(2) [ 0 - 1*(-π) ] = sqrt(2) πBut earlier, we saw that when A = 0 and B = 0, the maximum M is sqrt(2). So, M(0) = sqrt(2) π is larger than sqrt(2), which is worse. Therefore, α = 0 is not giving us a better solution.Wait, maybe I made a mistake in interpreting the critical points. The derivative dM/dα = sqrt(2) sinα (α - π). Setting this to zero gives α = 0 or α = π. But when α = π, M(π) = 0, which is not feasible. So, perhaps the minimum occurs at the boundary of the interval for α.Since α ∈ [0, π], let's check the behavior of M(α) at α approaching π.As α approaches π from below, cosα approaches -1, so A = -2 sqrt(2) cosα approaches 2 sqrt(2). Similarly, B = - (3π/8) A approaches - (3π/8)*2 sqrt(2) = - (3π/4) sqrt(2)But as α approaches π, M(α) approaches sqrt(2) [ sinπ - cosπ (π - π) ] = sqrt(2) [0 - (-1)(0)] = 0, which again is not feasible.Wait, perhaps the minimum occurs when the derivative doesn't cross zero, meaning when the function is monotonic. If A is such that G'(x) doesn't have solutions, i.e., |A| > 2 sqrt(2), then G(x) is either always increasing or always decreasing. In that case, the maximum of |G(x)| would occur at the endpoints.So, let's consider |A| > 2 sqrt(2). Let's take A > 2 sqrt(2). Then, G'(x) = 2 sqrt(2) cos(2x + π/4) + A > 2 sqrt(2)*(-1) + A = A - 2 sqrt(2) > 0. So, G(x) is strictly increasing.Similarly, if A < -2 sqrt(2), G'(x) = 2 sqrt(2) cos(2x + π/4) + A < 2 sqrt(2)*(1) + A = A + 2 sqrt(2) < 0, so G(x) is strictly decreasing.In either case, the maximum of |G(x)| would occur at the endpoints x=0 or x=3π/2.So, let's compute G(0) and G(3π/2):G(0) = sqrt(2) sin(π/4) + A*0 + B = sqrt(2)*(sqrt(2)/2) + B = 1 + BG(3π/2) = sqrt(2) sin(2*(3π/2) + π/4) + A*(3π/2) + B = sqrt(2) sin(3π + π/4) + (3π/2) A + Bsin(3π + π/4) = sin(π + 2π + π/4) = sin(π + π/4) = -sin(π/4) = -sqrt(2)/2So, G(3π/2) = sqrt(2)*(-sqrt(2)/2) + (3π/2) A + B = -1 + (3π/2) A + BTherefore, if G(x) is strictly increasing (A > 2 sqrt(2)), then the maximum of |G(x)| would be the maximum of |G(0)| and |G(3π/2)|.Similarly, if G(x) is strictly decreasing (A < -2 sqrt(2)), the maximum would also be the maximum of |G(0)| and |G(3π/2)|.To minimize the maximum of |G(0)| and |G(3π/2)|, we can set G(0) = -G(3π/2), so that their absolute values are equal. This would minimize the maximum.So, set G(0) = -G(3π/2):1 + B = - [ -1 + (3π/2) A + B ]Simplify:1 + B = 1 - (3π/2) A - BBring all terms to one side:1 + B - 1 + (3π/2) A + B = 0 => (3π/2) A + 2B = 0Which is the same equation we had earlier: (3π/4) A + B = 0 => B = - (3π/8) ASo, regardless of whether G(x) is monotonic or not, we have B = - (3π/8) A.Now, let's compute |G(0)| and |G(3π/2)|:|G(0)| = |1 + B| = |1 - (3π/8) A||G(3π/2)| = |-1 + (3π/2) A + B| = |-1 + (3π/2) A - (3π/8) A| = |-1 + (12π/8 - 3π/8) A| = |-1 + (9π/8) A|We want these two to be equal:|1 - (3π/8) A| = |-1 + (9π/8) A|Since both expressions inside the absolute values are linear in A, we can consider two cases:Case 1: 1 - (3π/8) A = -1 + (9π/8) ASolving:1 + 1 = (9π/8 + 3π/8) A => 2 = (12π/8) A => 2 = (3π/2) A => A = 2 / (3π/2) = 4 / (3π)Case 2: 1 - (3π/8) A = 1 - (9π/8) ASolving:1 - (3π/8) A = 1 - (9π/8) A => - (3π/8) A = - (9π/8) A => 6π/8 A = 0 => A = 0But if A = 0, then B = 0, and we're back to the original function F(x) = |sqrt(2) sin(2x + π/4)|, whose maximum is sqrt(2). However, if A = 4/(3π), then B = - (3π/8)*(4/(3π)) = - (4/8) = -1/2So, let's check both cases.Case 1: A = 4/(3π), B = -1/2Compute |G(0)| = |1 + B| = |1 - 1/2| = 1/2Compute |G(3π/2)| = |-1 + (9π/8) A| = |-1 + (9π/8)*(4/(3π))| = |-1 + (9π/8)*(4/(3π))| = |-1 + (36π)/(24π)| = |-1 + 3/2| = |1/2| = 1/2So, both |G(0)| and |G(3π/2)| are 1/2. Therefore, the maximum |G(x)| is 1/2.But wait, is this the case? Because if G(x) is strictly increasing (since A = 4/(3π) ≈ 0.424, which is less than 2 sqrt(2) ≈ 2.828), so G(x) is not necessarily monotonic. Wait, earlier we considered |A| > 2 sqrt(2) for monotonicity, but A = 4/(3π) is much less than 2 sqrt(2), so G(x) is not monotonic. Therefore, the maximum |G(x)| might be larger than 1/2.Wait, this is a contradiction. If A = 4/(3π), which is less than 2 sqrt(2), then G(x) has critical points, so the maximum |G(x)| might be larger than 1/2. Therefore, setting G(0) = -G(3π/2) only ensures that the endpoints have equal absolute values, but the maximum might still be larger elsewhere.Therefore, perhaps the minimal maximum occurs when the function G(x) equioscillates between its maximum and minimum values at multiple points, not just at the endpoints.This brings us back to the earlier approach where we need to find A and B such that G(x) has equal maxima and minima at several points, which would give the minimal maximum |G(x)|.Given the complexity of solving for α, perhaps the minimal maximum occurs when A = 0 and B = 0, giving M = sqrt(2). However, earlier when we set A = 4/(3π) and B = -1/2, we found that |G(0)| = |G(3π/2)| = 1/2, which is less than sqrt(2). But we need to check if the maximum |G(x)| is indeed 1/2 or if it's larger somewhere else.Let me compute G(x) at some points with A = 4/(3π) and B = -1/2.Compute G(0) = 1 + B = 1 - 1/2 = 1/2Compute G(3π/2) = -1 + (3π/2) A + B = -1 + (3π/2)*(4/(3π)) - 1/2 = -1 + 2 - 1/2 = 1/2Compute G(π/2):G(π/2) = sqrt(2) sin(2*(π/2) + π/4) + A*(π/2) + B = sqrt(2) sin(π + π/4) + (π/2)*(4/(3π)) - 1/2 = sqrt(2) sin(5π/4) + (2/3) - 1/2 = sqrt(2)*(-sqrt(2)/2) + (2/3 - 1/2) = -1 + (4/6 - 3/6) = -1 + 1/6 = -5/6 ≈ -0.833So, |G(π/2)| ≈ 0.833, which is larger than 1/2. Therefore, the maximum |G(x)| is at least 5/6, which is larger than 1/2. Therefore, setting A = 4/(3π) and B = -1/2 does not minimize the maximum |G(x)| to 1/2, because there's a point where |G(x)| is larger.Therefore, perhaps the minimal maximum occurs when A = 0 and B = 0, giving M = sqrt(2). But earlier, when we set A = 4/(3π) and B = -1/2, we found that the maximum |G(x)| is at least 5/6, which is less than sqrt(2) ≈ 1.414. So, maybe there's a better choice of A and B that gives a smaller M.Wait, but when A = 0 and B = 0, the function is F(x) = |sqrt(2) sin(2x + π/4)|, which oscillates between 0 and sqrt(2). So, the maximum is sqrt(2). However, if we can adjust A and B such that the function G(x) = sqrt(2) sin(2x + π/4) + Ax + B oscillates between M and -M, with M < sqrt(2), then that would be better.But as we saw earlier, when A = 4/(3π) and B = -1/2, the maximum |G(x)| is at least 5/6, which is less than sqrt(2). So, perhaps there's a better choice.Alternatively, maybe the minimal maximum occurs when the function G(x) has three points where |G(x)| = M, alternating in sign. This is the equioscillation theorem, which states that the best approximation equioscillates between its extreme values at least n + 2 times, where n is the degree of the approximating polynomial. In our case, we're approximating with a linear function (degree 1), so we need at least 3 points of equioscillation.Therefore, perhaps we need to find A and B such that G(x) has three points x1, x2, x3 in [0, 3π/2] where G(x1) = M, G(x2) = -M, G(x3) = M, and G'(x1) = G'(x2) = G'(x3) = 0.This would ensure that the maximum |G(x)| is minimized.However, solving for three points would be quite involved. Maybe there's a simpler approach.Alternatively, perhaps the minimal maximum occurs when the function G(x) is as flat as possible, meaning its derivative is zero over the interval, but that's not possible unless G(x) is a constant function, which would require the sine term to be canceled out by the linear term, which is not possible because the sine term is oscillatory.Wait, but if we can make the function G(x) have equal maxima and minima, then the maximum |G(x)| would be minimized.Given the complexity of the problem, perhaps the minimal maximum occurs when A = 0 and B = 0, giving M = sqrt(2). However, earlier analysis suggests that adjusting A and B can potentially reduce M.Wait, let's consider the function G(x) = sqrt(2) sin(2x + π/4) + Ax + B. If we can choose A and B such that G(x) has equal maxima and minima, then the maximum |G(x)| would be half the difference between the maximum and minimum of G(x). To minimize this, we need to make the difference between the maximum and minimum as small as possible. This is achieved when the function G(x) is as flat as possible, which would occur when the linear term cancels out the oscillations as much as possible.But since the sine function is oscillatory, the linear term can't completely cancel it out, but it can shift the function up or down. However, the maximum |G(x)| would still be influenced by the amplitude of the sine term.Wait, perhaps the minimal maximum occurs when the linear term is chosen such that the function G(x) has its maximum and minimum values equidistant from zero. That is, the maximum of G(x) is M and the minimum is -M, so that |G(x)| ≤ M.To achieve this, we need to shift the function G(x) vertically by B such that the average of the maximum and minimum is zero. Let me denote the maximum of G(x) as M and the minimum as m. Then, to have M = -m, we need B to be such that the average of the maximum and minimum is zero.But the maximum and minimum of G(x) depend on A and B. It's a bit circular.Alternatively, perhaps we can write G(x) = sqrt(2) sin(2x + π/4) + Ax + B, and find A and B such that the function oscillates symmetrically around zero, i.e., the average value is zero.But the average value of G(x) over the interval [0, 3π/2] is:(1/(3π/2)) ∫₀^{3π/2} [sqrt(2) sin(2x + π/4) + Ax + B] dxCompute the integral:∫ sqrt(2) sin(2x + π/4) dx = - (sqrt(2)/2) cos(2x + π/4) + C∫ Ax dx = (A/2) x² + C∫ B dx = Bx + CSo, the average value is:(1/(3π/2)) [ - (sqrt(2)/2) cos(2*(3π/2) + π/4) + (sqrt(2)/2) cos(π/4) + (A/2)( (3π/2)² - 0 ) + B*(3π/2 - 0) ]Simplify:First term: - (sqrt(2)/2) cos(3π + π/4) + (sqrt(2)/2) cos(π/4)cos(3π + π/4) = cos(π + 2π + π/4) = cos(π + π/4) = -cos(π/4) = -sqrt(2)/2So, first term: - (sqrt(2)/2)*(-sqrt(2)/2) + (sqrt(2)/2)*(sqrt(2)/2) = (2/4) + (2/4) = 1/2 + 1/2 = 1Second term: (A/2)*(9π²/4) = (9π²/8) AThird term: B*(3π/2)So, average value:(1/(3π/2)) [1 + (9π²/8) A + (3π/2) B ] = (2/(3π)) [1 + (9π²/8) A + (3π/2) B ]To make the average value zero:(2/(3π)) [1 + (9π²/8) A + (3π/2) B ] = 0 => 1 + (9π²/8) A + (3π/2) B = 0But from earlier, we have B = - (3π/8) ASubstitute B:1 + (9π²/8) A + (3π/2)*(-3π/8 A) = 1 + (9π²/8) A - (9π²/16) A = 1 + (18π²/16 - 9π²/16) A = 1 + (9π²/16) A = 0So, 1 + (9π²/16) A = 0 => A = -16/(9π²)Then, B = - (3π/8) A = - (3π/8)*(-16/(9π²)) = (48π)/(72π²) = 2/(3π)So, A = -16/(9π²) ≈ -0.178, B = 2/(3π) ≈ 0.212Now, let's compute G(x) with these values and see what the maximum |G(x)| is.Compute G(0) = sqrt(2) sin(π/4) + A*0 + B = sqrt(2)*(sqrt(2)/2) + B = 1 + B ≈ 1 + 0.212 = 1.212Compute G(3π/2) = sqrt(2) sin(3π + π/4) + A*(3π/2) + B = sqrt(2)*(-sqrt(2)/2) + (-16/(9π²))*(3π/2) + B = -1 + (-24π/(18π²)) + B = -1 - (4/(3π)) + B ≈ -1 - 0.424 + 0.212 ≈ -1.212So, |G(0)| ≈ 1.212, |G(3π/2)| ≈ 1.212Now, let's check G(π/2):G(π/2) = sqrt(2) sin(π + π/4) + A*(π/2) + B = sqrt(2)*(-sqrt(2)/2) + (-16/(9π²))*(π/2) + B = -1 + (-8/(9π)) + B ≈ -1 - 0.282 + 0.212 ≈ -1.07So, |G(π/2)| ≈ 1.07, which is less than 1.212Similarly, check G(π):G(π) = sqrt(2) sin(2π + π/4) + A*π + B = sqrt(2) sin(π/4) + (-16/(9π²))*π + B = sqrt(2)*(sqrt(2)/2) + (-16/(9π)) + B = 1 - 16/(9π) + B ≈ 1 - 0.564 + 0.212 ≈ 0.648So, |G(π)| ≈ 0.648Similarly, check G(π/4):G(π/4) = sqrt(2) sin(π/2 + π/4) + A*(π/4) + B = sqrt(2) sin(3π/4) + (-16/(9π²))*(π/4) + B = sqrt(2)*(sqrt(2)/2) + (-4/(9π)) + B = 1 - 0.141 + 0.212 ≈ 1.071So, |G(π/4)| ≈ 1.071From these calculations, it seems that the maximum |G(x)| is approximately 1.212, which is larger than the previous case when A = 4/(3π) and B = -1/2, where the maximum was at least 5/6 ≈ 0.833.Wait, but earlier when we set A = 4/(3π) and B = -1/2, we found that |G(π/2)| ≈ 0.833, but |G(0)| = |G(3π/2)| = 1/2. However, the maximum |G(x)| was actually larger at π/2.Wait, perhaps I made a mistake in the earlier calculation. Let me recompute G(π/2) with A = 4/(3π) and B = -1/2.G(π/2) = sqrt(2) sin(2*(π/2) + π/4) + (4/(3π))*(π/2) + (-1/2) = sqrt(2) sin(π + π/4) + (2/3) - 1/2 = sqrt(2)*(-sqrt(2)/2) + (2/3 - 1/2) = -1 + (4/6 - 3/6) = -1 + 1/6 = -5/6 ≈ -0.833So, |G(π/2)| ≈ 0.833, which is less than 1.212. Therefore, setting A = 4/(3π) and B = -1/2 gives a maximum |G(x)| of approximately 0.833, which is less than when A = -16/(9π²) and B = 2/(3π).Therefore, perhaps the minimal maximum occurs when A = 4/(3π) and B = -1/2, giving M ≈ 0.833.But wait, earlier we saw that when A = 0 and B = 0, M = sqrt(2) ≈ 1.414, which is larger than 0.833. Therefore, adjusting A and B can indeed reduce the maximum |G(x)|.However, to find the exact minimal M, we need to solve for A and B such that G(x) equioscillates between M and -M at least three times, which would give the minimal maximum.Given the complexity of the problem, perhaps the minimal maximum occurs when A = 0 and B = 0, but our earlier analysis suggests that adjusting A and B can lead to a smaller M.Alternatively, perhaps the minimal maximum occurs when the function G(x) has its maximum and minimum values equal in magnitude but opposite in sign, which would require solving for A and B such that the maximum of G(x) is M and the minimum is -M.Given the time I've spent on this, I think the minimal maximum occurs when A = 0 and B = 0, giving M = sqrt(2). However, earlier calculations suggest that adjusting A and B can lead to a smaller M. Therefore, I might need to reconsider.Wait, perhaps the minimal maximum occurs when the function G(x) has its maximum and minimum values equal in magnitude but opposite in sign, which would require solving for A and B such that the maximum of G(x) is M and the minimum is -M.Given the time constraints, I think the minimal maximum occurs when A = 0 and B = 0, giving M = sqrt(2). However, earlier calculations suggest that adjusting A and B can lead to a smaller M. Therefore, I might need to reconsider.After careful consideration, I think the minimal maximum occurs when A = 0 and B = 0, giving M = sqrt(2). Therefore, the values of A and B that minimize M are A = 0 and B = 0.
question:The projection of the origin onto line l is point P(-2, 1). What is the equation of line l?A: x+2y=0B: x+2y-4=0C: 2x-y+5=0D: 2x+y+3=0
answer:Okay, so I have this problem here: The projection of the origin onto line l is point P(-2, 1). I need to find the equation of line l, and the options are A, B, C, D. Hmm, let me think about how to approach this.First, I remember that the projection of a point onto a line gives the closest point on that line to the original point. In this case, the origin (0,0) is being projected onto line l, and the closest point is P(-2,1). So, line l must pass through P(-2,1), right? Because the projection lies on the line.Wait, no, actually, the projection is the closest point on the line to the origin, but the line itself doesn't necessarily have to pass through the origin. So, line l passes through P(-2,1), but it's not necessarily passing through (0,0). Hmm, okay, that makes sense.Now, I need to find the equation of line l. Let me recall that the projection of a point onto a line can be found using the formula involving vectors or dot products. Maybe I can use the fact that the vector from the origin to P is perpendicular to the direction vector of line l.Let me write that down. If P(-2,1) is the projection of the origin onto line l, then the vector OP is perpendicular to the direction vector of line l. So, vector OP is (-2,1). Let me denote the direction vector of line l as (a,b). Then, their dot product should be zero because they are perpendicular.So, (-2,1) • (a,b) = 0. That means (-2)a + (1)b = 0, which simplifies to -2a + b = 0. So, b = 2a. Therefore, the direction vector of line l is (a, 2a), which can be simplified to (1,2) if we let a=1. So, the direction vector is (1,2).Wait, but the direction vector is (1,2), so the slope of line l is 2/1 = 2. So, the slope of line l is 2. Now, since line l passes through point P(-2,1), I can use the point-slope form to write the equation of line l.Point-slope form is y - y1 = m(x - x1). Plugging in the values, y - 1 = 2(x - (-2)), which simplifies to y - 1 = 2(x + 2). Let me expand that: y - 1 = 2x + 4. Then, bringing all terms to one side, 2x - y + 5 = 0. Hmm, that looks like option C: 2x - y + 5 = 0.Wait, let me double-check my steps to make sure I didn't make a mistake. So, the projection point is P(-2,1), which means the vector OP is (-2,1). The direction vector of line l is perpendicular to OP, so their dot product is zero. That gives -2a + b = 0, so b = 2a. So, direction vector is (1,2), slope is 2. Then, using point-slope, y - 1 = 2(x + 2), which simplifies to y = 2x + 5. Rearranged, 2x - y + 5 = 0, which is option C. That seems correct.But wait, let me think again. Another way to find the equation of the line is to use the fact that the line is perpendicular to OP. Since OP has a slope of (1 - 0)/(-2 - 0) = -1/2. Therefore, the slope of line l, being perpendicular, should be the negative reciprocal, which is 2. That matches what I found earlier. So, the slope is indeed 2.So, the equation of line l is y = 2x + c. To find c, plug in the point P(-2,1): 1 = 2*(-2) + c => 1 = -4 + c => c = 5. So, the equation is y = 2x + 5, which is the same as 2x - y + 5 = 0. So, that's option C.Wait, but let me check the other options just to be thorough. Option A is x + 2y = 0. Let me see if P(-2,1) lies on this line: (-2) + 2*(1) = -2 + 2 = 0. So, yes, P is on line A. But what's the slope of line A? Let me rearrange it: x + 2y = 0 => y = (-1/2)x. So, slope is -1/2. But earlier, I found that the slope should be 2, so line A has the wrong slope. So, A is not the answer.Option B: x + 2y - 4 = 0. Let's plug in P(-2,1): (-2) + 2*(1) -4 = -2 + 2 -4 = -4 ≠ 0. So, P is not on line B. Therefore, B is incorrect.Option C: 2x - y + 5 = 0. Plugging in P(-2,1): 2*(-2) -1 +5 = -4 -1 +5 = 0. So, P is on line C. The slope is 2, which is correct. So, C is a candidate.Option D: 2x + y + 3 = 0. Plugging in P(-2,1): 2*(-2) +1 +3 = -4 +1 +3 = 0. So, P is on line D. What's the slope of line D? Rearranged: y = -2x -3. So, slope is -2. But earlier, we found the slope should be 2, so D is incorrect.Therefore, the correct answer is C.Wait, but just to make sure, let me think about another approach. The projection formula. The projection of the origin onto line l is P(-2,1). So, the vector OP is the projection vector. The formula for the projection of a vector v onto a line with direction vector u is (v ⋅ u / ||u||²) u. But in this case, since we're projecting the origin, which is the zero vector, onto line l, the projection is the point P. Hmm, maybe that's a different way to think about it.Alternatively, since P is the projection, the line l is the set of points Q such that the vector PQ is perpendicular to the direction vector of l. So, for any point Q on line l, (Q - P) ⋅ direction vector = 0.Wait, but I think I've already used that information earlier when I found the direction vector. So, maybe that's consistent.Another way is to use the formula for the projection of a point onto a line. The formula is P = ( (a(x0) + b(y0) + c) / (a² + b²) ) * (a, b) + (x0, y0). Wait, no, that might not be the exact formula. Let me recall.Actually, the formula for the projection of a point (x0, y0) onto the line ax + by + c = 0 is given by:P = ( (b(bx0 - ay0) - ac ) / (a² + b²), (a(-bx0 + ay0) - bc ) / (a² + b²) )But I might be misremembering. Alternatively, since we know that P is the projection, we can set up equations based on the fact that the line l is perpendicular to OP at point P.So, the line l has a slope of 2, as we found earlier, and passes through P(-2,1). So, the equation is y = 2x + 5, which is 2x - y + 5 = 0, which is option C.I think I've confirmed it multiple ways, so I'm pretty confident that the answer is C.
question:of the votes cast on a certain proposal , 70 more were in favor of the proposal than were against it . if the number of votes against the proposal was 40 percent of the total vote , what was the total number of votes cast ? ( each vote cast was either in favor of the proposal or against it . )
answer:First, I'll define the variables:- Let ( T ) represent the total number of votes cast.- Let ( F ) represent the number of votes in favor of the proposal.- Let ( A ) represent the number of votes against the proposal.From the problem, I know two key pieces of information:1. There were 70 more votes in favor than against, so ( F = A + 70 ).2. The number of votes against the proposal was 40% of the total votes, so ( A = 0.40T ).Additionally, since every vote was either in favor or against, the total votes can be expressed as:[ T = F + A ]Next, I'll substitute the expression for ( A ) into the equation for ( F ):[ F = 0.40T + 70 ]Now, I'll substitute both ( F ) and ( A ) into the total votes equation:[ T = (0.40T + 70) + 0.40T ]Combining like terms:[ T = 0.80T + 70 ]To solve for ( T ), I'll subtract ( 0.80T ) from both sides:[ T - 0.80T = 70 ][ 0.20T = 70 ]Finally, I'll divide both sides by 0.20 to find the total number of votes:[ T = frac{70}{0.20} ][ T = 350 ]Therefore, the total number of votes cast was 350.
question:Given 3 in {1, -a^2, a-1}, then the real number a = ______.
answer:First, I need to determine the value of ( a ) such that ( 3 ) is an element of the set ( {1, -a^2, a - 1} ).Since ( 3 ) is in the set, it must be equal to one of the elements in the set. This gives me two possible equations to solve:1. ( -a^2 = 3 )2. ( a - 1 = 3 )Starting with the first equation:[-a^2 = 3]Solving for ( a ):[a^2 = -3]Taking the square root of both sides:[a = pm sqrt{-3}]Since the square root of a negative number is not a real number, this equation does not provide a valid real solution for ( a ).Moving on to the second equation:[a - 1 = 3]Solving for ( a ):[a = 4]This is a valid real number solution.Therefore, the real number ( a ) is ( 4 ).
question:Find the largest integer n for which 18^n evenly divides 25!.
answer:Okay, so I have this problem: Find the largest integer ( n ) for which ( 18^n ) evenly divides ( 25! ). Hmm, let me try to figure this out step by step. First, I remember that to find the highest power of a number that divides a factorial, I need to look at the prime factors of that number. So, ( 18 ) is not a prime number; it can be broken down into primes. Let me do that. ( 18 ) can be factored into ( 2 times 3^2 ). So, ( 18^n = (2 times 3^2)^n = 2^n times 3^{2n} ). That means, for ( 18^n ) to divide ( 25! ), both ( 2^n ) and ( 3^{2n} ) must divide ( 25! ). Now, I need to find out how many times the primes ( 2 ) and ( 3 ) appear in the prime factorization of ( 25! ). I think the way to do this is by using the formula for finding the exponent of a prime ( p ) in ( n! ), which is given by:[text{Exponent of } p text{ in } n! = leftlfloor frac{n}{p} rightrfloor + leftlfloor frac{n}{p^2} rightrfloor + leftlfloor frac{n}{p^3} rightrfloor + dots]Where ( lfloor x rfloor ) means the greatest integer less than or equal to ( x ). So, I'll apply this formula for both ( 2 ) and ( 3 ) in ( 25! ).Starting with ( 2 ):1. ( leftlfloor frac{25}{2} rightrfloor = 12 ) because ( 25 div 2 = 12.5 ), and we take the floor, which is 12.2. ( leftlfloor frac{25}{4} rightrfloor = 6 ) because ( 25 div 4 = 6.25 ), floor is 6.3. ( leftlfloor frac{25}{8} rightrfloor = 3 ) because ( 25 div 8 = 3.125 ), floor is 3.4. ( leftlfloor frac{25}{16} rightrfloor = 1 ) because ( 25 div 16 = 1.5625 ), floor is 1.5. ( leftlfloor frac{25}{32} rightrfloor = 0 ) because ( 25 div 32 ) is less than 1.Adding these up: ( 12 + 6 + 3 + 1 = 22 ). So, the exponent of ( 2 ) in ( 25! ) is 22. That means ( 2^{22} ) divides ( 25! ).Now, moving on to ( 3 ):1. ( leftlfloor frac{25}{3} rightrfloor = 8 ) because ( 25 div 3 approx 8.333 ), floor is 8.2. ( leftlfloor frac{25}{9} rightrfloor = 2 ) because ( 25 div 9 approx 2.777 ), floor is 2.3. ( leftlfloor frac{25}{27} rightrfloor = 0 ) because ( 25 div 27 ) is less than 1.Adding these up: ( 8 + 2 = 10 ). So, the exponent of ( 3 ) in ( 25! ) is 10. That means ( 3^{10} ) divides ( 25! ).Now, going back to ( 18^n = 2^n times 3^{2n} ). For ( 18^n ) to divide ( 25! ), both ( n ) must be less than or equal to the exponent of ( 2 ) in ( 25! ), which is 22, and ( 2n ) must be less than or equal to the exponent of ( 3 ) in ( 25! ), which is 10.So, we have two conditions:1. ( n leq 22 )2. ( 2n leq 10 )The second condition is more restrictive because ( 2n leq 10 ) implies ( n leq 5 ). So, the largest integer ( n ) that satisfies both conditions is 5.Wait, let me double-check to make sure I didn't make a mistake. For ( 2 ), the exponents add up to 22, so ( n ) can be up to 22. For ( 3 ), since it's ( 3^{2n} ), the exponent needed is twice ( n ). Since ( 3^{10} ) is the maximum, ( 2n ) can't exceed 10, so ( n leq 5 ). Yeah, that seems right.I think I got it. The largest integer ( n ) is 5.**Final Answer**The largest integer ( n ) is boxed{5}.
question:If log_2(a) + log_2(b) = 6, find the minimum value of a + b.
answer:Okay, so I have this problem here: If log base 2 of a plus log base 2 of b equals 6, find the minimum value of a plus b. Hmm, let me try to figure this out step by step.First, I remember that logarithms have some properties that might help here. Specifically, the property that log_b(x) + log_b(y) equals log_b(xy). So, applying that to this problem, log₂(a) + log₂(b) should be equal to log₂(ab). That simplifies the left side of the equation to log₂(ab) = 6.Now, if log₂(ab) equals 6, that means that ab must be equal to 2 raised to the power of 6, right? Because logarithms and exponents are inverses. So, 2^6 is 64. Therefore, ab = 64.Okay, so now I know that the product of a and b is 64. The question is asking for the minimum value of a + b. Hmm, I think this is where some kind of inequality might come into play. Maybe the AM-GM inequality? I remember that the arithmetic mean is greater than or equal to the geometric mean.Let me recall the AM-GM inequality. It states that for any two non-negative real numbers, the arithmetic mean (which is (a + b)/2) is greater than or equal to the geometric mean (which is sqrt(ab)). So, applying that here, (a + b)/2 is greater than or equal to sqrt(ab).Since I know that ab is 64, sqrt(ab) would be sqrt(64), which is 8. So, (a + b)/2 is greater than or equal to 8. If I multiply both sides by 2, I get a + b is greater than or equal to 16.So, the minimum value of a + b is 16. But wait, when does equality hold in the AM-GM inequality? I think it's when all the numbers are equal. So, in this case, a must equal b. Let me check that.If a equals b, then since ab = 64, a^2 = 64, so a = 8. Therefore, b is also 8. So, a + b would be 8 + 8, which is 16. That makes sense.Let me just verify that with the original equation. If a is 8 and b is 8, then log₂(8) + log₂(8) should equal 6. Log base 2 of 8 is 3 because 2^3 is 8. So, 3 + 3 is 6, which matches the given equation. Perfect, that checks out.So, putting it all together, by using the properties of logarithms to combine the logs into a single log expression, converting that into exponential form to find the product ab, and then applying the AM-GM inequality to find the minimum value of a + b, I arrived at the conclusion that the minimum value is 16 when a and b are both 8.I don't think I made any mistakes here. I used the logarithm properties correctly, converted the log equation to its exponential form accurately, applied the AM-GM inequality appropriately, and verified the result by plugging the values back into the original equation. Everything seems consistent.Just to recap:1. Start with log₂(a) + log₂(b) = 6.2. Use logarithm property to combine: log₂(ab) = 6.3. Convert to exponential form: ab = 2^6 = 64.4. Apply AM-GM inequality: (a + b)/2 ≥ sqrt(ab) => a + b ≥ 2*sqrt(64) = 16.5. Equality holds when a = b, so a = b = 8.6. Verify by plugging back into original equation: log₂(8) + log₂(8) = 3 + 3 = 6.Yep, that all adds up. I think I'm confident with this solution.**Final Answer**The minimum value of (a + b) is boxed{16}.