$\lim_{x\to0}\left(x^{-2}ln\left(1-x\right)\right)$

$\frac{1+\sec\left(a\right)}{\tan\left(a\right)+\sin\left(a\right)}=\csc\left(a\right)$

$y^2-3y-28$

$\left(\frac{n^2}{2^n}\right)\left(x-4\right)^n$

$3x^2+5x-6;x=-5$

$\frac{d}{dx}\left(\frac{x^2\left(x-1\right)}{x+1}\right)$

$\lim_{x\to5}\left(\frac{2x^2-50}{x+5}\right)$