finiding a limit base on the limit of $e$ How can i find: $\lim_{x\to -\infty} \left(\cfrac{2x^3+5}{2x^3+3}\right)^{3x^3+5}$ 
I know that $\lim_{x\to \infty} \left(\cfrac{x+1}{x}\right)^{x}=e$ but can't see how it helps.

$$
\left(1+\frac{2}{2x^3+3}\right)^{\frac{3}{2}(2x^3+3)}\cdot \left(1+\frac{2}{2x^3+3}\right)^{-\frac{5}{2}}  \to e^{2\cdot \frac{3}{2}} \cdot 1=e^3.
$$
