# Why is this syntax to generate parentheses in math mode awry?

I am trying to wrap values in parentheses with

$\frac{\left (7-2)^8 \right \left (32-3)^5 \right}{5}$


However, pdflatex issues this error: ! Missing delimiter (. inserted).

Why? Taking out the \left and \right tokens eliminates the error.

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There's no need to add \left and \right, in general. The input \frac{(7-2)^8 (32-3)^5}{5} is what you need. Anyway, \right goes before the ). – egreg Apr 17 '12 at 21:48
After your first right you don't have a bracket – Marco Daniel Apr 17 '12 at 21:52

Actually \left and \right mean that the delimiters immediately following them are of variable height: TeX measures the formula between \left and \right and extends the delimiters so they completely envelop the expression. Therefore if your expression is just one line with symbols of normal height, it is easier to omit them: $(x+2)$. This is the usual case with inline equations. However, when you use displayed equations with large symbols, you need to have large delimiters: compare

$(\sum_i x_i)$


and

$\left(\sum_i x_i\right)$


Also, sometimes you need just one delimiter; the standard device is to use an empty delimiter (dot, .) on the other end, for example

$\left. \frac{df}{dx} \right|_{x\to 0}$

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It's not only easier, it's correct to omit \left and \right! – egreg Apr 17 '12 at 22:07
@egreg Some software that automatically produces tex code always inserts \left and right: I guess the authors think it is easier than to check the output. For example, in Maxima tex((x+y)*z); produces $$\left(y+x\right)\,z$$ – Boris Apr 17 '12 at 22:11
Well, that software is wrong. :) – egreg Apr 17 '12 at 22:13
@egreg depends on the definition of "wrong", I guess... – Boris Apr 17 '12 at 22:14