$-40\:-\:\left(-20\:-\:33\:+\:15\right)\:-\:\left(-80\right)\:+\:\left(13\:-\:91\right)$

$\frac{\tan\left(x\right)\sec\left(x\right)}{\csc\left(x\right)}=\tan^2\left(x\right)$

$\frac{4x^3y}{2x}$

$\frac{dy}{dx}=e^x\sqrt{1+y^2}$

$\frac{dy}{dx}=\frac{-6x^2}{y}$

$\int\left(x^2-2\right)\cdot ln\left(x\right)dx$

$x+3x^2=1$