$50x-10ay+50y-10ay$

$-x^2-2x+7$

$\int cot^4\left(\frac{1}{6}x\right)dx$

$\lim_{x\to\frac{\pi}{2}}\left(\frac{\sqrt{\cos\left(x\right)}-\cos\left(x\right)}{2.\sin\left(x\right).\cos\left(x\right)}\right)$

$\sqrt[4]{\frac{16}{16z^4}}$

$\frac{\left(x+y\right)^2-\left(x-y\right)^2}{xy}$

$\cos\left(x\right)\:\left(\tan\left(x\right)-1\right)=0$