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

$\left(x-5\right)\left(x=7\right)$

$\lim_{x\to\infty}\left(\frac{1-x^2}{x^2-8x-4}\right)$

$\int\left(\frac{u^2-2u+5}{\left(u-2\right)\left(u+2\right)\left(u-1\right)}\right)du$

$\frac{x+1}{x-3}+3\ge0$

$5\:\left(4+2\right)\:$

$\lim_{x\to a}\left(\frac{a^2-a^2}{a^4-a^4}\right)$