The fraction \frac{num}{den} are usually rendered by centering the numerator and the denominator.

Unfortunately, I find the result in the following MWE quite ugly:

```
\documentclass{article}
\begin{document}
If $r\neq 1$, then
\[
\sum_{k=0}^nr^k = \frac{1-r^{n+1}}{1-r}
\]
\end{document}
```

Indeed, the $r^{n+1}$ part is too big. I wish that the two – signs of a fraction of the form \frac{a-b}{c-d} to be vertically aligned (whatever the size of a,b,c and d) at the center of the fraction, in order to show the symmetry of the formula.

**How can I get such a result?**

Note: if it matters for the answer, I would like the alignment to work also for inline maths mode.

## Best Answer

If you really think this is what you want, here's the

`\diffratio`

macro:I have no doubt whatsoever that the normal

`\frac`

way is better.