$\left(x\cos\left(y\right)\right)\left(x\sin\left(y\right)\right)$

$\left(-7xyz+11x^2y^2z^3\right)^3$

$\left(2x+7y\right)^5$

$\lim_{x\to0}\left(\frac{\cos\left(3x\right)}{sin\left(2x\right)}\right)$

$\left(x+x^3\right)\left(x-x^3\right)$

$\frac{2x-xy^2}{4y-xy^2}$

$\cot\left(x\right)=-\frac{2\sqrt{5}}{5}$