$\lim_{x\to-6}\left(\frac{\left|x+6\right|}{x+6}\right)$

$16n^2-\left(m-n\right)^2$

$\frac{x}{x^2+2x}$

$\lim\:_{x\to\:\infty\:}\left(\frac{8\sqrt{x}+x^{-9}}{6x-5}\right)$

$4b^2-20b+25$

$\frac{d}{dx}\log\frac{10}{x}$

$\lim_{x\to0}\left(\frac{a^x-b^x}{c^x-d^x}\right)$