$cos\left(a\right)-cot\:\left(a\right)cos\left(a\right)=sen\left(a\right)$

$4\left(b+5\right)$

$\lim_{x\to1}\left(\frac{1-x^2}{2+\sqrt{x^3+3}}\right)$

$f\left(x\right)=\left(2x^{-2}+3\right)^{-3}$

$f\left(x\right)=\sqrt{x}^2$

$\lim_{x\to\infty}\sqrt{x^2+7x+3}-x$

$\int\left(7x+3\right)^2dx$