$\frac{x^2-4x+4}{x^2-x-2}$

$\left(2y\:-\:5\right)\left(2y\:+\:5\right)$

$\lim_{x\to\:\frac{\pi\:}{3}}\left(\frac{1-4cos^2x}{8sen\left(x-\frac{\pi\:}{3}\right)}\right)$

$2\cos^2x+\cos\left(2x\right)=1$

$\left(\left(\left(e^2t\right)\right)^2\right)\left(\left(t^2\right)^3\right)$

$4xy^2=x^2$

$\frac{dy}{dx}=0.08x\left(1-\frac{y}{1000}\right)$