QUESTION 7 Let f (x) = - -(x-1)4/3-_(x-1) 1/3+ 2. Find all values of x such that f"(x) =0 or f"(x) is undefined. As your answer please input the sum of all values of x for which or is undefined. 16 QUESTION 8 Let f( x) = -=(x-4)5/3-2(x-4) 2/3 -1. Find the interval (a, b) where f increases. As your answer please input a + b. QUESTION 9 Let f (x) = -x4+ 3x2-3. Find all critical points of f. As your answer please input the sum of all critical points. QUESTION 10 Let f(x) =x4-6x3-60x2 + 5x + 3. Find all solutions to the equation '(x) = 0. As your answer please enter the sum of values of x for which f( X)