You can scale then with \left\lvert
and \right\rvert
, just as with parentheses.
f_{3,2} = \left(\sqrt{13} - 2 - \left\lvert \frac{\sqrt{13}}{6} + 2
- 2\sqrt{7}\left(1 + \delta V\right) \right\rvert \right)/4
If you load the mathtools
package, you can use a \DeclarePairedDelimiter
command which simplifies scaling delimiters: writing \DeclarePairedDelimiter{\abs}{\lvert}{\rvert}
defines two commands: \abs
, which delimits its argument with \lvert
and \rvert
, and \abs*
, which does the same, but scaling it automatically.
Here's what this would look like for your code.
% in preamble
\usepackage{mathtools}
\DeclarePairedDelimiter{\paren}{(}{)}
\DeclarePairedDelimiter{\abs}{\lvert}{\rvert}
% document
f_{3,2} = \paren*{\sqrt{13} - 2 - \abs*{\frac{\sqrt{13}}{6} + 2
- 2\sqrt{7}\paren*{1 + \delta V}}}/4