数学测试

\sum_{i=0}^{n} i^{2}=\frac{\left(n^{2}+n\right)(2 n+1)}{6}

(\sum_{i=0}^{n} i^{2}=\frac{\left(n^{2}+n\right)(2 n+1)}{6})

$
\sum_{i=0}^{n} i^{2}=\frac{\left(n^{2}+n\right)(2 n+1)}{6}
$

[
\sum_{i=0}^{n} i^{2}=\frac{\left(n^{2}+n\right)(2 n+1)}{6}
]

[
f(x)=a_{1} x^{n}+a_{2} x^{n-1}+a_{3} x^{n-2}
]

\begin{equation}
\sum_{i=0}^{n} i^{2}=\frac{\left(n^{2}+n\right)(2 n+1)}{6}
\end{equation}