$-\left(2x-8\right)^2$

$9^2\:x\:\:9^9$

$\frac{n+1}{n^2+3n+1}x^n$

$\frac{dz}{dx}\left(x^2\cdot\:\:sin\left(z\right)+\left(x^2-1\right)\cdot\:\:y^4=z^6\right)$

$xydx+e^{-x^2}\left(y^2-1\right)dy$

$\frac{dy}{dx}=-\frac{\left(1+y^2\right)}{xy}$

$a\:-3b\:-8c\:+4b\:-a\:+8c$