Let f(x) be a polynomial of degree 5, and have extrema at x=1 and x=-1. If lim_x → 0((f(x))/x^3)=-5, then f(2)-f(-2) is equal to:

Let $\displaystyle f(x)$ be a polynomial of degree $\displaystyle 5$ , and have extrema at $\displaystyle x=1$ and $\displaystyle x=-1$. If $\displaystyle \lim _{x \rightarrow 0}\left(\frac{f(x)}{x^3}\right)=-5$, then $\displaystyle f(2)-f(-2)$ is equal to :