[Tex/LaTex] Big Parenthesis in an Equation


I have an equation contained inside \[...\], which automatically makes a \sum with sub- and superscripts turn big–so that the summation sign looks awkward inside parenthesis. Any idea how to make the parenthesis completely enclose the whole summation?

We have:
\[ \sum_{i=1}^n i = (\sum_{i=1}^{n-1} i) + n =
\frac{(n-1)(n)}{2} + n = \frac{n(n+1)}{2} \]

Best Answer

The usual thing to do is replace ( with \left( and ) with \right), which automatically expand to fit the material between them. Note that every \left... requires a \right... (but the type of bracket may be different, i.e. \left(...\right] also works).

I would typeset your equation as

\sum_{i=1}^n i = \left(\sum_{i=1}^{n-1} i\right) + n =
\frac{(n-1)(n)}{2} + n = \frac{n(n+1)}{2}

enter image description here

For manual control of sizes (most of the time you won't need these)

( \big( \Big( \bigg( \Bigg(


enter image description here