$15a^2\left(a+1\right)^3-5a^2\left(a+1\right)^2$

$\frac{\text{sen}\alpha\cos\alpha}{\text{tg}\alpha}=1-\text{sen}^2\alpha$

$-91\:x\:37\:$

$\frac{dy}{dx}=\frac{-y\ln\left(x\right)}{x\ln\left(y\right)}$

$10x^2+15x-5$

$\lim_{x\to0}\left(ln\left(x\right)^{-x}\right)$

$\tan^2x+3=4\sec^2x$