$\frac{dy}{dx}xy+x=1$

$\frac{d^2}{dx^2}\frac{x^3}{1-x}$

$\left(x+y\right)\:\left(z-t\right)$

$\tan\left(x\right)\cdot\csc\left(x\right)^2-\tan\left(x\right)\cdot\cot\left(x\right)^2$

$\tan^2\left(c\right)+\sin^2\left(c\right)+\cos^2\left(c\right)=\sec^2\left(c\right)$

$\lim_{x\to\infty}\left(\frac{2x}{\sqrt{x^2+1}}\right)$

$\left(2x-y\right)\left(4x^2\:+2xy+y^2\right)$