$$(sinh\frac{x}{a}+cosh\frac{x}{a})^{nx}$$
$\left(\sinh(\frac{x}{a})+\cosh(\frac{x}{a})\right)^{nx}$
$\frac{n\left(\ln(\sinh(\frac{x}{a})+\cosh(\frac{x}{a}))a+x\right)\left(\sinh(\frac{x}{a})+\cosh(\frac{x}{a})\right)^{nx}}{a}$
