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

$-30\::\:15$

$\frac{a^{12}-125b^{12}}{a^6+b^6}$

$\frac{d}{dx}\left(x+2\right)^8\left(x^2+e\right)^6$

$\lim_{x\to0}\left(\frac{x+1+e^x}{x^2}\right)$

$\frac{6}{3y-1}-\frac{1}{y}=\frac{4}{y\left(3y-1\right)}$

$1=ae^{-x+1}$