$\sec\left(x\right)-\sin\left(x\right)\tan\left(x\right)\csc^2\left(x\right)$

$\frac{1}{1-\sec\left(a\right)}+\frac{1}{1+\sec\left(a\right)}=2\cot^2\left(a\right)$

$\frac{dy}{dx}=x^2u$

$\:\left(\:pq\:+\:2\:\right)\:\left(\:pq\:-\:2\:\right)\:$

$1-9x^2$

$\frac{d}{dx}\left(xy^2+sin^2\left(x+y\right)=\frac{1}{2}\right)$

$\frac{d}{dx}\frac{m}{n}$