algebra precalculus - Find a limit without using L'Hopitals rule 9

Can someone please show me how to do this without using L'Hopitals rule:

$$\lim_{x \to \infty} \left(1 + \frac{a}{x}\right)^x$$

I know the limit is $e^a$, but I would like to know the steps taken to get to that answer.

thank you!