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question:Given the function f(x) = cos^4x 2sin xcos x sin^4x, 1. Find the minimal positive period of f(x); 2. Find the intervals where f(x) is monotonically increasing; 3. If x in left[0, frac{pi}{2}right], find the range of f(x).
answer:1. We can simplify f(x) as follows: begin{align*} f(x) &= cos^4x - 2sin xcos x - sin^4x &= (cos^2x + sin^2x)(cos^2x - sin^2x) - sin 2x &= 1 cdot (cos^2x - sin^2x) - sin 2x &= cos 2x - sin 2x &= sqrt{2}cosleft(2x + frac{pi}{4}right). end{align*} Consequently, since the cosine function has a period of 2pi, the minimal positive period T for f(x), considering the coefficient 2 in 2x, is: [ T = frac{2pi}{2} = pi. ] boxed{T = pi} 2. For the monotonicity intervals, observe that f(x) in its trigonometric form will be increasing whenever the cosine function is increasing. We can determine these intervals given the restriction that - pi leq 2x + frac{pi}{4} leq 2kpi, where k in mathbb{Z} (integers). Translating these bounds to the x-domain gives us: [ -frac{5pi}{8} + kpi leq x leq frac{3pi}{8} + kpi, ; k in mathbb{Z}. ] Therefore, the intervals where f(x) is monotonically increasing are given by: [ boxed{left[-frac{5pi}{8} + kpi, -frac{pi}{8} + kpiright], ; k in mathbb{Z}.} ] 3. To find the range of f(x) when x in left[0, frac{pi}{2}right], we can analyze the function's behavior on the period including this interval. Given the previous step, we know that f(x) is monotonically decreasing on left[0, frac{3pi}{8}right] and monotonically increasing on left[frac{3pi}{8}, frac{pi}{2}right]. Therefore, the minimum value of f(x) on this interval will be at the boundary of the aforementioned monotonically increasing interval, which is fleft(frac{3pi}{8}right); thus, it is: [ min f(x) = -sqrt{2}. ] The maximum value will be either at x = 0 or x = frac{pi}{2}. Calculating both yields: [ f(0) = sqrt{2}cosleft(0 + frac{pi}{4}right) = 1, ] [ fleft(frac{pi}{2}right) = sqrt{2}cosleft(pi + frac{pi}{4}right) = -1. ] As such, the range of f(x) for x in left[0, frac{pi}{2}right] is boxed{left[-sqrt{2}, 1right]}.
question:The maximum value of the function y = 1 + sin x is ___.
answer:Since sin x leq 1, the maximum value of y = 1 + sin x is 2. Therefore, the answer is boxed{2}.
question:Find the product of all positive integral values of n such that n^2 41n + 408 = p for some prime number p. Note that there is at least one such n.
answer:- We firstly observe that since n^2 - 41n = n(n-41), at least one factor must be even (since one number between n and n-41 is even), implying n^2 - 41n is even. Thus, n^2 - 41n + 408 is also even. Therefore, the prime p must be 2. - We solve for n in the equation n^2 - 41n + 408 = 2, or equivalently n^2 - 41n + 406 = 0. - The product of the solutions to the quadratic ax^2 + bx + c = 0 is c/a. Here, a = 1, b = -41, and c = 406. The product of the roots is 406. - The sum of the roots is given by -b/a = 41. Since the sum and the product of the roots are both positive integers, both solutions are positive integers. Conclusion: The product of all positive integral values of n that satisfy the equation is boxed{406}.
question:Beckett is 12 and is three years younger than Olaf, while Shannen is two years younger than Olaf. If Jack is five more than twice as old as Shannen, what is the sum of the ages of all 4 people?
answer:Let's start by figuring out the ages of each person step by step. 1. Beckett is 12 years old. 2. Olaf is 3 years older than Beckett, so Olaf is 12 + 3 = 15 years old. 3. Shannen is 2 years younger than Olaf, so Shannen is 15 - 2 = 13 years old. 4. Jack is five more than twice as old as Shannen, so Jack is 2 * 13 + 5 = 26 + 5 = 31 years old. Now, let's add up the ages of all four people: Beckett (12) + Olaf (15) + Shannen (13) + Jack (31) = 12 + 15 + 13 + 31 = 71 The sum of the ages of all four people is boxed{71} years.