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question:It is known that the average price of a basketball, soccer ball, and volleyball is 36 yuan each. A basketball is 10 yuan more expensive than a volleyball, and a soccer ball is 8 yuan more expensive than a volleyball. How much does each soccer ball cost?

answer:First, I need to determine the individual prices of a basketball, a soccer ball, and a volleyball based on the given information.I know that the average price of these three items is 36 yuan. This means the total cost of one basketball, one soccer ball, and one volleyball is 108 yuan.Let’s denote the price of a volleyball as ( V ). According to the problem, a basketball is 10 yuan more expensive than a volleyball, so the price of a basketball ( B ) is ( V + 10 ). Similarly, a soccer ball is 8 yuan more expensive than a volleyball, so the price of a soccer ball ( S ) is ( V + 8 ).Now, I can set up the equation for the total cost:[B + S + V = 108]Substituting the expressions for ( B ) and ( S ):[(V + 10) + (V + 8) + V = 108]Combining like terms:[3V + 18 = 108]Solving for ( V ):[3V = 90][V = 30]Now that I know the price of a volleyball is 30 yuan, I can find the price of a soccer ball:[S = V + 8 = 30 + 8 = 38]

question:Given the function f(x)= frac {1}{2}x^{2}+ax-2ln x(ainmathbb{R}). (1) If a=1, find the intervals of monotonicity and the extremum of the function f(x). (2) If the function f(x) is monotonically decreasing on the interval (0,2], find the range of the real number a.

answer:Okay, so I have this function f(x) = (1/2)x² + a x - 2 ln x, where a is a real number. There are two parts to the problem. Starting with part (1): If a = 1, I need to find the intervals where the function is increasing or decreasing and also determine its extremum points. First, I know that to find the monotonicity of a function, I need to look at its first derivative. So, let's compute f'(x). Given f(x) = (1/2)x² + x - 2 ln x (since a = 1). The derivative of (1/2)x² is x, the derivative of x is 1, and the derivative of -2 ln x is -2*(1/x) = -2/x. So, putting it all together, f'(x) = x + 1 - 2/x.Hmm, that looks right. So, f'(x) = x + 1 - 2/x. To make this easier to analyze, maybe I can combine the terms over a common denominator. Multiplying numerator and denominator appropriately, I get:f'(x) = (x² + x - 2)/x.Wait, let me check that. If I have x + 1 - 2/x, to combine them, I can write it as (x² + x - 2)/x. Yes, that's correct because:x = x²/x, 1 = x/x, and -2/x remains as is. So, adding them up: x² + x - 2 over x.Now, to find the critical points, I need to set f'(x) equal to zero and solve for x.So, (x² + x - 2)/x = 0. The numerator must be zero, so x² + x - 2 = 0. Let's solve this quadratic equation.Using the quadratic formula: x = [-b ± sqrt(b² - 4ac)]/(2a). Here, a = 1, b = 1, c = -2.So, discriminant D = 1² - 4*1*(-2) = 1 + 8 = 9.Thus, x = [-1 ± 3]/2. So, x = (-1 + 3)/2 = 2/2 = 1, and x = (-1 - 3)/2 = -4/2 = -2.But since our function f(x) is defined for x > 0 because of the ln x term, we can ignore the negative root x = -2. So, the critical point is at x = 1.Now, to determine the intervals of monotonicity, we need to analyze the sign of f'(x) around x = 1.The domain is (0, ∞). Let's pick test points in the intervals (0,1) and (1, ∞).First interval: (0,1). Let's choose x = 0.5.Plug into f'(x): (0.5² + 0.5 - 2)/0.5 = (0.25 + 0.5 - 2)/0.5 = (-1.25)/0.5 = -2.5. So, f'(x) is negative here, meaning the function is decreasing on (0,1).Second interval: (1, ∞). Let's choose x = 2.Plug into f'(x): (4 + 2 - 2)/2 = (4)/2 = 2. So, f'(x) is positive here, meaning the function is increasing on (1, ∞).Therefore, the function decreases on (0,1) and increases on (1, ∞). So, x = 1 is a local minimum.To find the value of the function at x = 1: f(1) = (1/2)(1)² + 1 - 2 ln 1 = 0.5 + 1 - 0 = 1.5. So, the minimum value is 1.5 at x = 1.Since the function tends to infinity as x approaches 0 from the right and as x approaches infinity, there's no maximum value.Okay, that seems solid. So, part (1) is done.Moving on to part (2): If the function f(x) is monotonically decreasing on the interval (0,2], find the range of the real number a.So, for f(x) to be decreasing on (0,2], its derivative f'(x) must be less than or equal to zero for all x in (0,2].From part (1), we already found that f'(x) = (x² + a x - 2)/x.So, f'(x) ≤ 0 on (0,2]. That implies:(x² + a x - 2)/x ≤ 0 for all x in (0,2].Since x is positive in (0,2], the inequality is equivalent to x² + a x - 2 ≤ 0 for all x in (0,2].So, x² + a x - 2 ≤ 0 for all x in (0,2].We can rearrange this inequality to solve for a:a x ≤ -x² + 2Since x is positive, we can divide both sides by x without changing the inequality direction:a ≤ (-x² + 2)/x = (2 - x²)/x = 2/x - x.So, a ≤ 2/x - x for all x in (0,2].Therefore, a must be less than or equal to the minimum value of the function g(x) = 2/x - x on the interval (0,2].So, we need to find the minimum of g(x) on (0,2].Let's analyze g(x) = 2/x - x.First, let's find its derivative to see where it's increasing or decreasing.g'(x) = derivative of 2/x is -2/x², and derivative of -x is -1. So, g'(x) = -2/x² - 1.Since x is in (0,2], x² is positive, so -2/x² is negative, and -1 is also negative. Therefore, g'(x) is always negative on (0,2]. That means g(x) is strictly decreasing on (0,2].Therefore, the minimum value of g(x) on (0,2] occurs at the right endpoint x = 2.Compute g(2): 2/2 - 2 = 1 - 2 = -1.Therefore, the minimum value of g(x) on (0,2] is -1.Thus, to satisfy a ≤ g(x) for all x in (0,2], a must be less than or equal to -1.Therefore, the range of a is (-∞, -1].Wait, let me double-check. Since g(x) is decreasing, its minimum is at x = 2, which is -1. So, a has to be ≤ -1.Yes, that makes sense. So, if a is less than or equal to -1, then for all x in (0,2], a ≤ 2/x - x, which ensures that x² + a x - 2 ≤ 0, hence f'(x) ≤ 0, so f is decreasing.If a were greater than -1, then at x = 2, we would have a > -1, so 2/x - x = -1, so a > -1 would mean that at x = 2, a > g(2), which would make x² + a x - 2 > 0, so f'(x) > 0, which contradicts the requirement that f is decreasing on (0,2]. Therefore, a must be ≤ -1.So, part (2) is done.**Final Answer**(1) The function is decreasing on (0, 1) and increasing on (1, infty) with a minimum value of boxed{dfrac{3}{2}} at x = 1.(2) The range of a is boxed{(-infty, -1]}.

question:Let lines a and b have direction vectors overrightarrow {e_{1}} and overrightarrow {e_{2}} respectively, and let plane α have a normal vector overrightarrow {n}. Then among the following inferences: ① If overrightarrow {e_{1}}parallel overrightarrow {e_{2}} and overrightarrow {e_{1}}parallel overrightarrow {n}, then b is parallel to α. ② If overrightarrow {e_{1}}parallel overrightarrow {n} and overrightarrow {e_{2}}parallel overrightarrow {n}, then a is parallel to b. ③ If overrightarrow {e_{1}}parallel overrightarrow {n}, b is not contained in α, and overrightarrow {e_{1}} is perpendicular to overrightarrow {e_{2}}, then b is parallel to α. ④ If overrightarrow {e_{1}}parallel overrightarrow {e_{2}} and overrightarrow {e_{1}}parallel overrightarrow {n}, then b is perpendicular to α. Identify the correct proposition(s).

answer:Alright, so I've got this problem about lines and planes with direction vectors and normal vectors. It's a bit confusing, but let me try to break it down step by step.First, let's understand the given information:- Line **a** has a direction vector **e₁**.- Line **b** has a direction vector **e₂**.- Plane **α** has a normal vector **n**.There are four inferences given, and I need to figure out which ones are correct. Let's go through each one by one.**Inference ①:** If **e₁** is parallel to **e₂** and **e₁** is parallel to **n**, then **b** is parallel to **α**.Hmm, okay. So if **e₁** is parallel to **e₂**, that means lines **a** and **b** are parallel to each other because their direction vectors are the same. Also, if **e₁** is parallel to **n**, that means line **a** is perpendicular to plane **α** because the direction vector of the line is parallel to the normal vector of the plane.But does that mean line **b** is parallel to plane **α**? Wait, if **a** is perpendicular to **α**, and **a** is parallel to **b**, then **b** should also be perpendicular to **α**, right? So if **b** is perpendicular to **α**, it can't be parallel to **α**. That means inference ① is incorrect.**Inference ②:** If **e₁** is parallel to **n** and **e₂** is parallel to **n**, then **a** is parallel to **b**.Okay, so both **e₁** and **e₂** are parallel to **n**. That means both lines **a** and **b** are perpendicular to plane **α** because their direction vectors are parallel to the normal vector of the plane. If two lines are both perpendicular to the same plane, they must be parallel to each other. So this makes sense. Inference ② is correct.**Inference ③:** If **e₁** is parallel to **n**, **b** is not contained in **α**, and **e₁** is perpendicular to **e₂**, then **b** is parallel to **α**.Alright, let's parse this. **e₁** is parallel to **n**, so line **a** is perpendicular to plane **α**. **b** is not contained in **α**, so it doesn't lie entirely within the plane. Also, **e₁** is perpendicular to **e₂**, which means the direction vector of line **a** is perpendicular to the direction vector of line **b**.If **a** is perpendicular to **α**, and **b** is not in **α**, but **a** is perpendicular to **b**, does that mean **b** is parallel to **α**? Let me visualize this. If **a** is sticking straight out of the plane, and **b** is not in the plane, but **b** is perpendicular to **a**, then **b** must be lying in a direction that's parallel to the plane. Because if it were at an angle, it wouldn't be perpendicular to **a**. So, yeah, I think **b** has to be parallel to **α**. So inference ③ is correct.**Inference ④:** If **e₁** is parallel to **e₂** and **e₁** is parallel to **n**, then **b** is perpendicular to **α**.Wait, this seems similar to inference ①. If **e₁** is parallel to **e₂**, then **a** and **b** are parallel. And if **e₁** is parallel to **n**, then **a** is perpendicular to **α**, so **b** should also be perpendicular to **α**. But earlier, I thought that if **a** is perpendicular to **α**, then **b** being parallel to **a** would also be perpendicular to **α**. So why did I say inference ① was incorrect?Let me double-check. Inference ① says that **b** is parallel to **α**, but if **b** is parallel to **a**, and **a** is perpendicular to **α**, then **b** should be perpendicular, not parallel. So inference ① is incorrect, and inference ④ is correct.Wait, this is conflicting with my earlier conclusion. Maybe I made a mistake.Let me clarify:- If **e₁** is parallel to **e₂**, then **a** and **b** are parallel.- If **e₁** is parallel to **n**, then **a** is perpendicular to **α**.- Therefore, **b** should also be perpendicular to **α** because it's parallel to **a**.So inference ④ is correct, and inference ① is incorrect.But earlier, I thought inference ③ was correct, but now I'm confused about ④.Wait, no, in inference ④, it's saying that **b** is perpendicular to **α**, which makes sense because **b** is parallel to **a**, and **a** is perpendicular to **α**. So inference ④ is correct.But in inference ①, it's saying **b** is parallel to **α**, which is wrong because **b** should be perpendicular. So ① is incorrect.So, summarizing:- ①: Incorrect- ②: Correct- ③: Correct- ④: CorrectWait, but earlier I thought ③ was correct, but now I'm not sure. Let me think again.Inference ③: **e₁** is parallel to **n**, so **a** is perpendicular to **α**. **b** is not in **α**, and **e₁** is perpendicular to **e₂**. So **a** is perpendicular to **b**.If **a** is perpendicular to **α**, and **a** is perpendicular to **b**, then **b** must be parallel to **α**. Because if **b** were not parallel, it would have a component perpendicular to **α**, which would mean **a** and **b** aren't purely perpendicular. So yes, **b** must be parallel to **α**. So ③ is correct.So, in the end, inferences ②, ③, and ④ are correct.But wait, in the initial analysis, I thought ④ was correct, but in the first step, I thought ① was incorrect. So, the correct inferences are ②, ③, and ④.But let me check again.- ①: **e₁** || **e₂** and **e₁** || **n** ⇒ **b** || **α**. But **b** should be perpendicular, so ① is incorrect.- ②: **e₁** || **n** and **e₂** || **n** ⇒ **a** || **b**. Correct.- ③: **e₁** || **n**, **b** not in **α**, and **e₁** ⊥ **e₂** ⇒ **b** || **α**. Correct.- ④: **e₁** || **e₂** and **e₁** || **n** ⇒ **b** ⊥ **α**. Correct.So, all except ① are correct. But in the initial thought process, I thought ③ was incorrect, but upon reevaluation, it's correct.So, the correct inferences are ②, ③, and ④.But wait, in the initial problem, the user mentioned that in the first analysis, ③ was incorrect, but upon reevaluation, it was correct. So, the final answer should include ②, ③, and ④.But in the initial assistant answer, it was ② and ③. So, there's a discrepancy.Let me see.If ④ is correct, then the answer should include ②, ③, and ④.But in the initial assistant answer, it was only ② and ③. So, perhaps the assistant made a mistake.Alternatively, maybe I'm overcomplicating.Let me think about ④ again.If **e₁** || **e₂** and **e₁** || **n**, then **b** is perpendicular to **α**.Yes, because **e₂** is parallel to **n**, so **b** is perpendicular to **α**. So ④ is correct.Therefore, the correct inferences are ②, ③, and ④.But in the initial assistant answer, it was only ② and ③. So, perhaps the assistant missed ④.Alternatively, maybe ④ is incorrect because **b** could be parallel to **α** or perpendicular, depending on other factors.Wait, no. If **e₂** is parallel to **n**, then **b** must be perpendicular to **α**. There's no other possibility. So ④ is correct.Therefore, the correct inferences are ②, ③, and ④.But in the initial problem, the user only concluded ② and ③. So, perhaps there's a misunderstanding.Alternatively, maybe in ④, **b** is not necessarily perpendicular because it could be parallel to **α** if **e₂** is parallel to **n**. Wait, no. If **e₂** is parallel to **n**, then **b** is perpendicular to **α**.So, I think ④ is correct.Therefore, the correct inferences are ②, ③, and ④.But in the initial assistant answer, it was only ② and ③. So, perhaps the assistant made a mistake.Alternatively, maybe I'm misinterpreting ④.Let me read ④ again:④ If **e₁** || **e₂** and **e₁** || **n**, then **b** is perpendicular to **α**.Yes, because **e₂** is parallel to **n**, so **b** is perpendicular to **α**. So ④ is correct.Therefore, the correct inferences are ②, ③, and ④.But in the initial problem, the user only concluded ② and ③. So, perhaps the user made a mistake.Alternatively, maybe in ④, **b** is not necessarily perpendicular because **b** could be parallel to **α** if **e₂** is parallel to **n**. Wait, no. If **e₂** is parallel to **n**, then **b** is perpendicular to **α**.So, I think ④ is correct.Therefore, the correct inferences are ②, ③, and ④.But in the initial assistant answer, it was only ② and ③. So, perhaps the assistant missed ④.Alternatively, maybe the problem is in Chinese, and the translation is slightly off.But assuming the problem is as stated, I think ②, ③, and ④ are correct.But to be safe, let me check again.- ①: Incorrect- ②: Correct- ③: Correct- ④: CorrectSo, the correct answer is ②, ③, and ④.But in the initial assistant answer, it was only ② and ③. So, perhaps the assistant made a mistake.Alternatively, maybe in ④, **b** is not necessarily perpendicular because **b** could be parallel to **α** if **e₂** is parallel to **n**. Wait, no. If **e₂** is parallel to **n**, then **b** is perpendicular to **α**.So, I think ④ is correct.Therefore, the correct inferences are ②, ③, and ④.But in the initial problem, the user only concluded ② and ③. So, perhaps the user made a mistake.Alternatively, maybe I'm overcomplicating.In any case, based on my analysis, the correct inferences are ②, ③, and ④.

question:How many different lists ( a, b, c, d ) of distinct odd positive integers with ( a < b < c < d ) have the property that ( a + b + c + d = 24 ) ?

answer:Okay, so I have this problem where I need to find how many different lists of four distinct odd positive integers ( a, b, c, d ) exist such that ( a < b < c < d ) and their sum is 24. Hmm, interesting. Let me try to figure this out step by step.First, since all numbers are odd and distinct, and they have to be in increasing order, I can start by considering the smallest possible value for ( a ). The smallest odd positive integer is 1, so maybe I can start there.If ( a = 1 ), then the next number ( b ) has to be at least 3, right? Because they have to be distinct and increasing. So, ( b ) can be 3, 5, 7, etc. But since the total sum is 24, I can't have ( b ) too large, otherwise the sum of the four numbers would exceed 24.Let me try ( a = 1 ) and ( b = 3 ). Then ( c ) has to be at least 5, and ( d ) at least 7. Let's see what the sum would be: 1 + 3 + 5 + 7 = 16. That's way below 24, so I need to increase the numbers.Wait, maybe I should think about how much is left after choosing ( a ) and ( b ). If ( a = 1 ) and ( b = 3 ), then the sum of ( c ) and ( d ) needs to be 24 - 1 - 3 = 20. So, ( c + d = 20 ). Since ( c ) and ( d ) are distinct odd integers greater than 3, let's list possible pairs:- ( c = 5 ), ( d = 15 ) (since 5 + 15 = 20)- ( c = 7 ), ( d = 13 ) (7 + 13 = 20)- ( c = 9 ), ( d = 11 ) (9 + 11 = 20)So that gives me three possible lists when ( a = 1 ) and ( b = 3 ): [1, 3, 5, 15], [1, 3, 7, 13], and [1, 3, 9, 11].Now, let's try ( a = 1 ) and ( b = 5 ). Then the sum of ( c ) and ( d ) would be 24 - 1 - 5 = 18. So, ( c + d = 18 ). Again, ( c ) has to be greater than 5, so possible pairs:- ( c = 7 ), ( d = 11 ) (7 + 11 = 18)That's one list: [1, 5, 7, 11].What if ( b = 7 )? Then ( c + d = 24 - 1 - 7 = 16 ). But ( c ) has to be greater than 7, so the smallest ( c ) can be is 9, which would make ( d = 7 ), but that's not possible because ( d ) has to be greater than ( c ). So, this doesn't work. Therefore, ( b ) can't be 7 when ( a = 1 ).So, for ( a = 1 ), we have four possible lists: three with ( b = 3 ) and one with ( b = 5 ).Next, let's try ( a = 3 ). Then ( b ) has to be at least 5. Let's see what happens.If ( a = 3 ) and ( b = 5 ), then ( c + d = 24 - 3 - 5 = 16 ). ( c ) has to be greater than 5, so the smallest ( c ) can be is 7, which would make ( d = 9 ). So, that gives us [3, 5, 7, 9].What if ( b = 7 )? Then ( c + d = 24 - 3 - 7 = 14 ). ( c ) has to be greater than 7, so the smallest ( c ) can be is 9, which would make ( d = 5 ), but that's not possible because ( d ) has to be greater than ( c ). So, this doesn't work. Therefore, ( b ) can't be 7 when ( a = 3 ).So, for ( a = 3 ), we only have one possible list: [3, 5, 7, 9].What if ( a = 5 )? Then ( b ) has to be at least 7. Let's check:If ( a = 5 ) and ( b = 7 ), then ( c + d = 24 - 5 - 7 = 12 ). ( c ) has to be greater than 7, so the smallest ( c ) can be is 9, which would make ( d = 3 ), but that's not possible because ( d ) has to be greater than ( c ). So, this doesn't work. Therefore, ( a ) can't be 5 or higher because the sum would be too small.So, compiling all the possible lists:- From ( a = 1 ): - [1, 3, 5, 15] - [1, 3, 7, 13] - [1, 3, 9, 11] - [1, 5, 7, 11] - From ( a = 3 ): - [3, 5, 7, 9]That's a total of 5 different lists.I think that's all. I don't see any other possibilities because increasing ( a ) beyond 3 doesn't give valid lists, and we've exhausted all possibilities for ( a = 1 ) and ( a = 3 ).

question:The function f(x)=2sin ωx (ω > 0) is monotonically increasing on the interval [0, frac{π}{3}], and the maximum value on this interval is sqrt{2}. Determine the value of ω.

answer:Okay, so I have this problem here: the function f(x) = 2 sin(ωx) where ω is greater than 0. It says that this function is monotonically increasing on the interval [0, π/3], and the maximum value on this interval is √2. I need to find the value of ω.Alright, let's start by recalling what it means for a function to be monotonically increasing. A function is monotonically increasing on an interval if its derivative is non-negative throughout that interval. So, I should probably find the derivative of f(x) and ensure it's non-negative on [0, π/3].The function is f(x) = 2 sin(ωx). Let's find its derivative. The derivative of sin(u) with respect to x is cos(u) times the derivative of u with respect to x. So, f'(x) = 2 * ω cos(ωx). So, f'(x) = 2ω cos(ωx).Since ω is positive, the sign of f'(x) depends on cos(ωx). For f'(x) to be non-negative on [0, π/3], cos(ωx) must be non-negative on that interval. So, cos(ωx) ≥ 0 for all x in [0, π/3].Now, when is cos(θ) non-negative? Cosine is non-negative in the intervals where θ is between -π/2 + 2πk and π/2 + 2πk for integers k. But since ω is positive and x is in [0, π/3], ωx will be in [0, ωπ/3]. So, we need cos(ωx) ≥ 0 for all x in [0, π/3], which implies that ωπ/3 must be less than or equal to π/2. Because if ωπ/3 were greater than π/2, then at some point in the interval, cos(ωx) would become negative, right?So, setting up the inequality: ωπ/3 ≤ π/2. Let's solve for ω. Multiply both sides by 3/π: ω ≤ (π/2) * (3/π) = 3/2. So, ω must be less than or equal to 3/2.But wait, the problem also says that the maximum value of f(x) on [0, π/3] is √2. Let's think about that. The function f(x) = 2 sin(ωx). The maximum value of sin is 1, so the maximum value of f(x) would be 2*1 = 2. But here, the maximum is given as √2, which is less than 2. That suggests that the function doesn't reach its full maximum within the interval [0, π/3]. Instead, it reaches √2 somewhere in that interval.So, the maximum occurs at some point x in [0, π/3], and at that point, f(x) = √2. So, 2 sin(ωx) = √2. Dividing both sides by 2, we get sin(ωx) = √2/2.What angle has a sine of √2/2? That's π/4 and 3π/4 in the unit circle. But since the function is increasing on [0, π/3], the maximum occurs at the right endpoint, which is x = π/3. Wait, is that necessarily true?Hold on, if the function is monotonically increasing on [0, π/3], then its maximum should occur at the right endpoint, which is x = π/3. So, f(π/3) should be equal to √2.So, let's compute f(π/3): 2 sin(ω * π/3) = √2. So, sin(ωπ/3) = √2/2.So, sin(θ) = √2/2 implies θ = π/4 + 2πk or θ = 3π/4 + 2πk for integers k. But since ω is positive and x is in [0, π/3], θ = ωπ/3 must be in the first quadrant because the function is increasing and we're looking for the first occurrence where sin(θ) = √2/2.Therefore, ωπ/3 = π/4. Solving for ω: ω = (π/4) * (3/π) = 3/4.Wait, but earlier we had that ω must be less than or equal to 3/2. 3/4 is less than 3/2, so that's fine. So, ω = 3/4.But let me just double-check. If ω = 3/4, then f(x) = 2 sin((3/4)x). Let's check if it's increasing on [0, π/3].Compute the derivative: f'(x) = 2*(3/4) cos((3/4)x) = (3/2) cos((3/4)x). Since cos((3/4)x) is positive for x in [0, π/3], because (3/4)x ranges from 0 to (3/4)*(π/3) = π/4, and cosine is positive in [0, π/2]. So, yes, the derivative is positive on [0, π/3], so the function is indeed increasing there.And the maximum value is at x = π/3: f(π/3) = 2 sin((3/4)*(π/3)) = 2 sin(π/4) = 2*(√2/2) = √2. Perfect, that matches the given condition.So, I think ω is 3/4.Wait, but just to make sure, what if the maximum wasn't at the endpoint? Suppose the function reaches its maximum somewhere inside the interval. But since the function is increasing on the entire interval, it can't have a maximum in the middle; it must be at the right endpoint. So, that's why we can safely say that f(π/3) is the maximum.Alternatively, if the function had a critical point inside [0, π/3], then the maximum could be there. But since it's monotonically increasing, there are no critical points in the interval except possibly at the endpoints. So, yeah, the maximum is at x = π/3.Therefore, ω must be 3/4.**Final Answer**The value of ( omega ) is boxed{dfrac{3}{4}}.

question:Given the universal set U=mathbb{R}, A={xmid frac{1}{|x-1|} < 1}, and B={xmid x^{2}-5x+4 > 0}, find Acap(neg_U B).

answer:Okay, so I have this problem where the universal set is all real numbers, U = ℝ. There are two sets defined: A and B. I need to find the intersection of set A with the complement of set B in the universal set U, which is written as A ∩ (¬U B). First, let me understand what each set represents. Set A is defined as {x | 1/|x - 1| < 1}. That means all real numbers x such that the reciprocal of the absolute value of (x - 1) is less than 1. Set B is defined as {x | x² - 5x + 4 > 0}, which is a quadratic inequality. I think I should start by solving the inequality for set A. So, 1/|x - 1| < 1. To solve this, I can manipulate the inequality to find the values of x that satisfy it. First, I know that 1 divided by something is less than 1, which means that the something must be greater than 1. So, if 1/|x - 1| < 1, then |x - 1| > 1. That makes sense because if the denominator is larger, the whole fraction becomes smaller. So, |x - 1| > 1 implies that x - 1 is either greater than 1 or less than -1. Let me write that down:x - 1 > 1 or x - 1 < -1Solving the first inequality: x - 1 > 1, so x > 2.Solving the second inequality: x - 1 < -1, so x < 0.Therefore, set A is all real numbers less than 0 or greater than 2. So, A = (-∞, 0) ∪ (2, ∞).Next, I need to find set B, which is defined by the inequality x² - 5x + 4 > 0. To solve this quadratic inequality, I should factor the quadratic expression.Let me factor x² - 5x + 4. I need two numbers that multiply to 4 and add up to -5. Hmm, -1 and -4. Yes, because (-1) * (-4) = 4 and (-1) + (-4) = -5. So, the factored form is (x - 1)(x - 4) > 0.Now, to solve (x - 1)(x - 4) > 0, I can use a sign chart. The critical points are x = 1 and x = 4. These divide the real number line into three intervals:1. x < 12. 1 < x < 43. x > 4I'll test each interval to see where the product is positive.For x < 1, let's pick x = 0: (0 - 1)(0 - 4) = (-1)(-4) = 4, which is positive.For 1 < x < 4, let's pick x = 2: (2 - 1)(2 - 4) = (1)(-2) = -2, which is negative.For x > 4, let's pick x = 5: (5 - 1)(5 - 4) = (4)(1) = 4, which is positive.So, the inequality (x - 1)(x - 4) > 0 is satisfied when x < 1 or x > 4. Therefore, set B is (-∞, 1) ∪ (4, ∞).Now, I need to find the complement of set B in the universal set U, which is ℝ. The complement of B, denoted as ¬U B, consists of all real numbers not in B. Since B is (-∞, 1) ∪ (4, ∞), the complement will be the interval where B is not, which is [1, 4].So, ¬U B = [1, 4].Finally, I need to find the intersection of set A and ¬U B. Set A is (-∞, 0) ∪ (2, ∞), and ¬U B is [1, 4]. The intersection of these two sets will be the overlap between them.Let me visualize this on the number line. Set A has two parts: everything less than 0 and everything greater than 2. The complement of B is from 1 to 4, including the endpoints. So, the overlap between A and ¬U B will be the part of A that is within [1, 4].Looking at set A, the part that overlaps with [1, 4] is (2, ∞) intersected with [1, 4], which is (2, 4]. The other part of A, which is (-∞, 0), doesn't overlap with [1, 4] at all.Therefore, A ∩ (¬U B) = (2, 4].I should double-check my steps to make sure I didn't make any mistakes. Starting with set A: 1/|x - 1| < 1 leads to |x - 1| > 1, which gives x < 0 or x > 2. That seems correct.For set B: x² - 5x + 4 > 0 factors to (x - 1)(x - 4) > 0, and testing intervals gives x < 1 or x > 4. That also seems correct.The complement of B is [1, 4], which makes sense because it's the interval where the inequality doesn't hold.Finally, intersecting A and ¬U B: A is (-∞, 0) ∪ (2, ∞), and ¬U B is [1, 4]. The overlap is (2, 4], which is what I concluded.I think that's the correct answer.

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