$$
\int\_0^{\infty}\frac{2\left[\,x - \tanh\left(\,x\,\right)\,\right]}
{\sinh\left(\,x\,\right)\tanh^{2}\left(\,x\,\right)}\,\mathrm{d}x
$$
I know that the answer is $\pi^{2}/4$.

I tried to change $\sinh\left(\,x\,\right)$ and $\tanh\left(\,x\,\right)$ to series but it's hard. I hope to give me full answers with different methods.