$\frac{cos^2\left(t\right)}{sen\left(t\right)}+\sin\left(t\right)=\csc\left(t\right)$

$4xy\frac{dx}{dy}=x^2+1$

$\left(b^{1+m}\right)\left(b^{2m}\right)$

$\left(d^3-d\right)y\:=\:3x$

$\lim_{x\to3}\left|1-x\right|$

$\frac{\left(x+1\right)^9}{\left(3x-9\right)^{10}}$

$\frac{\cot x-1}{1-\tan x}=\cot x$