$\frac{1\:+\:\tan\left(a\right)}{1+\:\cot\left(a\right)}=\tan\left(a\right)$

$\lim_{x\to\infty}\left(\frac{3x^3-6x^2+3x+6}{-3x^2+4x-4}\right)$

$\frac{x+4}{5}=\frac{x}{3}$

$6sen^2x-x^5$

$\frac{tan\left(x\right)\:-\:cot\:\left(x\right)}{tan\:\left(x\right)\:+\:cot\left(x\right)}+2\:cos^2\left(x\right)\:=1$

$\int\frac{1}{sqrt\left(x^2+2x+2\right)}dx$

$\int\left(\frac{\left(1+e^2\right)}{\left(1-e^2\right)}\right)dx$