$5^2\cdot5^4\cdot5^{-3}$

$\left[-2+\left(-8+4-6+7\right)\right]-\left[\left(3+8-7-5\right)+8\right]$

$a^3-b^9$

$x\frac{dy}{dx}-y=x\:+2\:$

$\tan x\:\sec x\:\sin x=\tan^2x$

$20\frac{1}{2}-2\frac{1}{2}+4\frac{5}{6}-2\frac{1}{6}$

$9\cos^2\left(x\right)-4\sin^2\:\left(x\right)$