# Parenthesis Around Fraction - How Make Bigger

• May 15th 2010, 07:49 PM
DeanSchlarbaum
Parenthesis Around Fraction - How Make Bigger
Given the following equation --

$\displaystyle \pm(\frac{1+i}{\sqrt2})=\sqrt{i}$

How can the parenthesis -- (. . . .) -- around fraction be made larger so as to encompass the entire fraction?
• May 15th 2010, 08:31 PM
dwsmith
Quote:

Originally Posted by DeanSchlarbaum
Given the following equation --

$\displaystyle \pm(\frac{1+i}{\sqrt2})=\sqrt{i}$

How can the parenthesis -- (. . . .) -- around fraction be made larger so as to encompass the entire fraction?

\big( \big)
\bigg( \bigg)
• May 15th 2010, 09:06 PM
Soroban
Hello, DeanSchlarbaum!

Quote:

Given the following equation: .
$\displaystyle \pm(\frac{1+i}{\sqrt2})=\sqrt{i}$

How can the parenthesis (. . . .) around a fraction be made larger?

[math ]\pm \left( \frac{1+i}{\sqrt2} \right) \;=\; \sqrt{i}[/math ]

. . $\displaystyle \pm\left(\frac{1+i}{\sqrt2}\right)\;=\;\sqrt{i}$

This works for any size fraction:

. . $\displaystyle \left[ \frac{\dfrac{1}{4}+\dfrac{2}{3}}{5 + \dfrac{1}{2}} \right]$

[math ] \left[ \frac{\dfrac{1}{4}+\dfrac{2}{3}}{5 + \dfrac{1}{2}} \right] [/math ]
• May 16th 2010, 12:16 AM
Opalg
Quote:

Originally Posted by Soroban
Hello, DeanSchlarbaum!

[math ]\pm \left( \frac{1+i}{\sqrt2} \right) \;=\; \sqrt{i}[/math ]

. . $\displaystyle \pm\left(\frac{1+i}{\sqrt2}\right)\;=\;\sqrt{i}$

This works for any size fraction:

. . $\displaystyle \left[ \frac{\dfrac{1}{4}+\dfrac{2}{3}}{5 + \dfrac{1}{2}} \right]$

[math ] \left[ \frac{\dfrac{1}{4}+\dfrac{2}{3}}{5 + \dfrac{1}{2}} \right] [/math ]

\left and \right are certainly very useful. But they sometimes make parentheses that are larger than you really want. For example, there are situations where something like $\displaystyle \left(1+\sum_{n=1}^Nx_n^2\right)^{1/2}<\infty$ might be improved by writing it as $\displaystyle \biggl(1+\sum_{n=1}^Nx_n^2\biggr)^{1/2}<\infty$, or even $\displaystyle \Bigl(1+\sum_{n=1}^Nx_n^2\Bigr)^{1/2}<\infty$, using \biggl and \biggr (or \Bigl and \Bigr) instead of \left and \right.