$\:2\left(x+yz\right)$

$2x^2-3x^2+4x\cdot2x^2-3$

$\left(4x^3+x\right)^2$

$2\frac{dy}{dx}+6y=12\sin\left(9\cdot x\right)$

$\lim_{x\to\infty}\left(\frac{\sqrt[2]{x+1}}{3x+1}\right)$

$cx\left(2x-1\right)\left(2x+5\right)$

$\frac{d}{dx}\left(\frac{-1}{1+x^2}+\frac{-1}{x}\right)$