This is a \(\infty \frac{x^3}{e^x-1}\) with few symbols.

Eq 1,

\[ \begin{equation} \int_0^\infty \frac{x^3}{e^x-1}\,dx = \frac{\pi^4}{15} \label{eq:sample} \end{equation} \]

Eq 2 without starting with beginning equation tagger,

\[ \Gamma(z) = \int_0^\infty t^{z-1}e^{-t}dt\,. \]