can someone further explain it? thanks.

8. Let f(x) = 2r - 6:2 + 30. For each of the following questions, you MUST show supporting work with calculus and algebra. Answers without supporting work will not receive credit. (a) (3 points) Determine the critical point(s) of f(x). Show all supporting work. f(x)= 2x^4-6x^2+30 f(x)= 8x43-18x^2 f'(x)=24x^2-36x= quadratic equation which yields x= + or - sqrt3/2 I plugged in f'(x) to the quadratic after having set it to 0 to find my critical points after my calculations I got positive and negative square root of three over two. Critical Point(s): +sqrt3/2,-sqrt3/2 (b) (6 points) If we just consider f(a) = -2 + 82 - 10 on the interval [-1, 2], determine th absolute minimum and absolute maximum values of f(r) on the given interval. Justify you conclusions with all supporting work. f(x)=-2(2x^3-64x+5) x=0.0781399