Very Urgent

Find the derivative at each critical point and determine the local extreme values. 5 ) y = J -x2 - 4x+8, xs 1 -x2 + 12x - 8, x> 1 Provide an appropriate response. 6) Let f(x) = x3 - 4x (a) Does f'(0) exist? (b) Does f' (2) exist? (c) Does f'(-2) exist? (d) Determine all extrema of f. Determine whether the function satisfies the hypotheses of the Mean Value Theorem for the given interval. 7) s(t) = ~+(2 - t), [-1,5]