$3x^3y^2z+6xy$

$\frac{-1-\cos\left(x\right)^2+2\sin\left(x\right)^2}{\sin\left(x\right)^2}$

$n^6-14n^4+49n^2-36$

$\left(\tan\left(a\right)^2-sec\left(a\right)^2\right)\left(1-\cos\left(a\right)\right)$

$\left(a-2\right)\left(3a-2b\right)$

$\lim_{x\to0}\left(\frac{x^3}{log\left(x^2+10\right)}\right)$

$2x-x-2y$