$x^2+7x-7\left(x^2+x\right)$

$52x^2y^2+16xy^3+26z$

$20m^2n^2\:-\:60mnp\:+\:45p^2$

$\lim_{x\to0}\left(\frac{1}{x\sin\left(x\right)}\right)$

$x^2-2x.-1-1^2$

$\log\left(z\right)=-2i$

$\int\left(\frac{\left(x\right)}{\left(x-1\right)\left(2x+5\right)^2\left(3x+1\right)^2}\right)dx$