Given that f (x) is differentiable at x = 0, f (0) = 0, f '(0) = 2, what is the limit of F (sin3x) / X when x approaches 0

Given that f (x) is differentiable at x = 0, f (0) = 0, f '(0) = 2, what is the limit of F (sin3x) / X when x approaches 0

When x approaches 0, sin3x is 0, and f (0) = 0, so f (sin3x) = 0. Therefore, by using the law of lobita, the upper and lower derivatives of X can be changed to 3cos3xf '(sin3x), and X tends to 0, so the answer is 6