$-2\left(z+3\right)-z=\left(z+2\right)-4\left(z+2\right)$

$x-4x^2y+6xy^2\cdot axy$

$-10x^2-60x+20$

$\lim_{x\to0}\left(ln\left(6x\right)\cdot\arctan\left(2x\right)\right)$

$\frac{d}{dx}\log_{31}\left(2x-4\right)$

$\left(x^3.y^4\right)\left(x^5y\right)$

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