$\frac{7x^3+2x}{9x}$

$\frac{dy}{dx}=-10^{-6}\left(x^2-81\right)$

$\lim_{x\to6}\frac{x^2-13x+42}{x-6}$

$\sqrt{a^5}$

$\sqrt[3]{\sqrt[4]{x^{-6}}}-\sqrt[3]{x^{-2}y}.\sqrt[3]{xy^{-1}}-\sqrt[10]{x^{-8}\sqrt[5]{x^{15}}}$

$2\left(-y-4z\right)-5\left(6z-6y\right)$

$2y+5=4y+13$