() Let f(x) = x-8x+4. (a) Find the x-value c of the critical point of f(x), and compute f(c). The x-value of the critical point is c = The value of f(c) = (b) Compute the value of f(x) at the endpoints of the interval [0,8]. f(0) = f(8) (c) Determine the minimum and maximum values of f(x) on [0,8]. Minimum value = Maximum value = (d) Find the extreme values of f(x) on [0, 1]. Minimum value = Maximum value=