$\left(\frac{1}{2}\cdot\left(x+6\right)^2\right)+\left(-2\left(x+6\right)-1\cdot\left(-2\cdot\left(x+6\right)\right)\right)+\left(-4\left(x+6\right)-1\cdot\:\left(-4\cdot\left(x+6\right)\right)\right)=10$

$\lim_{x\to0}\left(\frac{5x-2x^2}{5x}\right)$

$\frac{\tan\left(x\right)}{1+\cos\left(x\right)}+\frac{\tan\left(x\right)}{1-\cos\left(x\right)}=\frac{2}{\sin\left(x\right)\cos\left(x\right)}$

$\lim_{x\to0}\left(\frac{sin2x.cos^2x}{tanx}\right)$

$\frac{2ab}{3a\:}$

$\frac{2}{5}+\sqrt{13}+0.3682$

$15mn^4+3m^4n^4-12m^3n^2x$