$\frac{1+\sin\left(x\right)}{\cos\left(x\right)}+\frac{\cos\left(x\right)}{\sin\left(x\right)}=\frac{1+\sin\left(x\right)}{\sin\left(x\right)\cdot\cos\left(x\right)}$

$\cos\:^2\left(y\right)=sen^2\left(y\right)+cos\left(2y\right)$

$\frac{3}{y};\:y=-5$

$\frac{d}{dx}\sqrt[7]{lnx}$

$\frac{1}{y-16}y'\:=k$

$\frac{dy}{dt}=e^{3y+3t}$

$-2x^3+x^2-x-1;\:x=-2$