I need help solving problem 9, I have tried twice and was able to get half way through but the second derivative part messed me up

In problems 6 - 10, a function and values of x so that f '(x) = 0 are given. Use the Second Derivative Test to determine whether each point (x, f(x)) is a local maximum, a local minimum or neither 6. f(x) = 2x -15x-+.6, x=0, 5. 7. g(x) = x - 3x-- 9x+7, x=-1, 3. 8. h(x) = x4- 8x2- 2, x=-2, 0,2. 9. f(x) = sin (x) , x = JT/2, JU, 3JT/2