# Summation as exponent

 x^{\displaystyle\sum_{k=1}^n {n \choose k}p^k + 1} How can I make the exponent look smaller?

• \displaystyle is causing the exponent to be over-large. if the reason you're using that is to get the limits above and below the sum, then use \sum\limits instead. but gonzalo's answer is better. – barbara beeton May 16 '14 at 1:35

Instead fo trying to accommodate such a big expression as a superscript, I'd suggest you to use a name for it and then explain this name:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

$x^{\alpha},\quad\text{where } \alpha=\sum_{k=1}^n \binom{n}{k} p^k + 1.$

$x^{\alpha},\text{ where } \alpha=\sum_{k=1}^n \binom{n}{k} p^k + 1$.

\end{document} Also, \choose is an old command; use \binom{}{} instead.

I would probably remove the \displaystyle and enclose it in parentheses, like this: and then shrink it down even further using \scriptscriptstyle, like this: which I find plenty readable... although Gonzalo's suggestion of giving it an intermediate name is probably the clearest, unless you're all out of variable names to spare. :)

\documentclass{article}
\usepackage{amsmath}
\begin{document}

$x^{(\sum_{k=1}^n \binom{n}{k} p^k + 1)}$

$x^{(\raisebox{.35pt}{$\scriptscriptstyle{\sum_{k=1}^n \binom{n}{k} p^k + 1}$})}$

\end{document}