In general, you can't standardise this: the over-large ones have to be straight as TeX can not stretch otherwise, for smaller sizes it depends on the font in use, the shape, and how many designed sizes there are is controlled by the font not TeX.

Almost all fonts will use a slanted design for the designed glyphs before TeX falls back to the straight extender, so one way to standardise on sloping design unless you have *really* tall entries is to use a font that has more sizes of designed sqrt size than the original cm fonts. The yhmath font is one such font:

```
\documentclass{article}
\usepackage{amsmath,yhmath}
\begin{document}
(1)
\[\Delta F_0 = \sqrt{\sum_{i=1}^n\left(\frac{\delta F_0}{\delta x_i}\Delta x_i\right)^2}\]
(2)
\[\Delta F_0 = \sqrt{6.044 \cdot 10^{-6}\text{m}^2}\]
\end{document}
```

It's the usual problem due to the setting of the math extension font done by `lmodern.sty`

, which defines `OMX/lmex/m/n`

for it with this *completely wrong* font definition file:

```
\ProvidesFile{omxlmex.fd}[2009/10/30 v1.6 Font defs for Latin Modern]
\DeclareFontFamily{OMX}{lmex}{}
\DeclareFontShape{OMX}{lmex}{m}{n}{%
<->sfixed*lmex10%
}{}
\endinput
```

This means that `lmex10`

is used no matter what the surrounding font size is. This *might* seem to work at standard sizes (it doesn't, however, try with `\sum`

in a subscript).

I usually suggest to reinstate the Computer Modern math extension font, but applying the fact that nowadays arbitrary scaling is possible.

```
\documentclass[a4paper,fontsize=14pt]{scrbook}
\usepackage{mathtools}
\usepackage{lmodern}
\DeclareFontShape{OMX}{cmex}{m}{n}{%
<-7.5>cmex7
<7.5-8.5>cmex8
<8.5-9.5>cmex9
<9.5->cmex10
}{}
\DeclareSymbolFont{largesymbols}{OMX}{cmex}{m}{n}
\begin{document}
\[
a = \sqrt[m]{\sum_{i=1}^{n}b_{i}^m}.
\]
\end{document}
```

## Best Answer

I guess you are looking for the services of the

`newtxmath`

math font package. Note that if you use it, you should probably also use the companion`newtxtext`

text font package. Do check, though, if you want to (or are allowed to) use a Times Roman clone for your document.