$1+-3+-1$

$\frac{d^2}{dx^2}\left(e^xtan\:y\right)$

$\frac{4x^2+6x+4}{x+1}$

$\:27x^3-216$

$xy^2dx+\left(y+x^2y\right)dy=0$

$\frac{1+\sin\left(x\right)}{1-\sin\left(x\right)}=\frac{1}{\sec\left(x\right)-\tan\left(x\right)}^2$

$y=\left(u^2-u\right)\left(\frac{1}{x}\right)$