$\left(r^2-8\right)\left(r^2+8\right)$

$\frac{r+1}{2}\ge1$

$-8x^2y\left(-3x^5y^3\right)$

$\frac{1}{\sin\left(a\right).\cos\left(a\right)}-\frac{\cos\left(a\right)}{\sin\left(a\right)}:\tan\left(a\right)$

$-ln\left(x-1\right)+ln\left(x-2\right)\:=\:y^2$

$6y^2\:+\:9y^5$

$2x+3y-12=0$