$\frac{d}{dx}5sen^2x$

$\lim_{x\to0}\left(3xtan\left(\left(\frac{\pi\:}{2}\right)-x\right)\right)$

$\left(25x^2-36y^2\right)^3$

$x^2-9x-36$

$\lim_{x\to\infty}\left(x-\sqrt{x^2-4x}\right)$

$\lim\:_{x\to\:\infty\:}\left(\frac{3x^2+2x}{5x^3-3x^2}\right)$

$\frac{x+2}{4}-\frac{x-14}{6}$