$\frac{\left(x+2\right)\left(x+1\right)}{x-3}$

$\frac{3-x}{2}=-4$

$\left(1-sen^2\left(a\right)\right)cot^2\left(a\right)+1$

$\int\:\left(5x-2\right)cos\left(x\right)dx$

$\lim_{x\to0}\frac{\sqrt{2}-\sqrt{1+cosx}}{3sin^2x}$

$\frac{1}{3}\sin\left(-\frac{1}{4}x\right)$

$\left(-3m^2n\right)\left(-5mn^3\right)$