Find the second derivatives.

a. y = f(x) = 8x + 3x2 - 13

b. y = f(x) = ex + x2 - (2x - 4)2

c. y = f(x) = x/3 + 4 - (x - 3)2(x2 + 2)

d. y = f(x) = 2loge(x2 + 4x) - [(x - 2)/(x + 3)]2