$3\left(3\:+\:7b\right)$

$x^2-5x-6$

$\lim_{y\to w}\left(\frac{x\left(cos\left(yt\right)+cos\left(wt\right)\right)}{w^2-y^2}\right)$

$\frac { 7 a } { a }$

$\left(4mn+\frac{1}{8}\right)^3$

$\frac{d^2}{dx^2}\left(3x-x^2\cos\left(x\right)\right)$

$\frac{dy}{dx}=\sqrt{y-x}$