$\lim_{x\to1}\:\:\frac{1}{\sin\left(x\right)}-\frac{x}{\sin\left(x\right)}$

$9z-6z-1$

$\frac{-3\sin\left(a\right)}{\cos\left(a\right)}$

$\left(784\cdot567\right)\cdot\left(4003\right)$

$\frac{r}{r}$

$\:4x^{4n}-16y^{2m}$

$11m^2-12mn^2+10-\left(6m^3+10m^2n-5mn+13\right)$