$\left(x-8y\right)\left(x+8y\right)$

$\frac{5x}{x-1}=4$

$\left(5+y\right)\left(8+y\right)$

$\lim_{x\to0}\left(\frac{2\:cos\:x+2}{\left(x-\pi\right)^2}\right)$

$\int\frac{1}{\left(x^2+13\right)\sqrt{x+7}}dx$

$\frac{\left(y^2-1\right)^3}{3}-\frac{\left(2y^2-2\right)^3}{3}$

$a^2-9a+18$