exp(x)=1+x+ (1)x 44+x 55!+ +x nn!+ \begin{multline} \exp(x) = 1 + x + \cdots \\ \frac{x^4}4 + \frac{x^5}{5!} + \cdots \\ \cdots + \frac{x^n}{n!} + \cdots \end{multline}