$9m+12$

$=\frac{2x-880}{\left(x^2-22x+125\right)^2}$

$\lim_{x\to1}\left(\frac{9sin\left(9\pi x\right)}{cos\left(\pi x\right)+x}\right)$

$\frac{2x+1}{x\left(x+1\right)\left(x^2+4x+6\right)}$

$\left(\frac{2r^3t^6}{5u^9}\right)^4$

$2x^2-3\le5$

$\left(2m-n\right)\left(2m+n\right),\:cuando\:m=1\:y\:n=4$