Let f : R $\to$  R be a differentiable function satisfying f$’$(3) + f$’$(2) = 0.

Then $\underset{x\to 0}{\lim }{\left(\frac{1+f(3+x)-f(3)}{1+f(2-x)-f(2)}\right)}^{\frac{1}{x}}$ is equal to: