Given the function f (x) = X3 + AX2 + BX + C (where a, B, C are constants), if y = f (x) obtains the maximum and minimum values respectively when x = - 1 and x = - 13, then a=______ .

Given the function f (x) = X3 + AX2 + BX + C (where a, B, C are constants), if y = f (x) obtains the maximum and minimum values respectively when x = - 1 and x = - 13, then a=______ .

F ′ (x) = 3x2 + 2aX + B, ∵ f (− 1) = 0f (− 13) = 0, ∵ 3 − 2A + B = 013 − 23a + B = 0, B = 2