MHB Integration of hyperbolic function

[paulmdrdo1]

i don't know how start. please help.

$\displaystyle\int xsech^2(x^2)dx$

 

[alyafey22]

Hint :

$$\frac{d}{dx} \tanh(x)=\text{sech}^2(x)$$

What about

$$\frac{d}{dx} \tanh(x^2)$$