$\int\left(\frac{\left(-15\right)}{\left(15x+12\right)^4}\right)dx$

$x^2-8x+21$

$3y+2z-4z$

$\frac{x}{x-3}-\frac{14x-9}{x^2+5-24}$

$\left(uv\:+\:6\right)^2$

$\int sen^42xcos^32xdx$

$\lim_{x\to0}\left(\frac{4\tan\left(x\right)+1-\cos\left(x\right)}{x\sec\left(x\right)}\right)$