$cos\frac{x}{2}-1=0$

$\left(x\:-\:2\right)\left(3x^2\:-\:x\right)$

$3x+5\:con\:x=26$

$8\tan b+12=3\tan b+7$

$\:\frac{\left(x+y\right)^2+\left(x-y\right)^2}{x^2+y^2}$

$-2-\left\{-1-\left[-4-5+1+\left(-3-2+4\right)-10\right]-20\right\}-4$

$\frac{dy}{dx}=\frac{1}{\sqrt{y}-y}$