集合論

\(\sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}\)

\[
  \sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}
  \tag{3}
\]

\[ \sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6} \tag{3} \] inline math $\sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}$