Question

Suppose f(x) = e^ax+ e^bx, where a ≠ b, and that f"(x) - 2f'(x) - 15 f(x) = 0 for all x. Then the product ab is equal to

(A) 25

(B) 9

(C) - 15

(D) -9 

Answer 1

Answer is (C) - 15