$a2+6a\:+9$

$\left(9x-3y+5\right)+\left(-x-y+4\right)+\left(5x+4y-9\right)$

$\lim_{x\to0}\left(\frac{\sin\left(2x\right)}{\sqrt{x+1}-1}\right)$

$\left(d^2+2\right)^{-2}+1$

$\lim_{x\to\infty}\left(\frac{2x+1}{2x-2}-1\right)\cdot\frac{2x+1}{1}$

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

$\frac{dy}{dx}=\frac{2y^2}{xy-2x^2}$