$\frac{d^2u}{dx^2}=-1$

$\left(x^3+y^3\right)\left(x^6+x^3y^3+y^6\right)$

$\frac{0.4}{0.12}\frac{\left(1\:\right)}{0.12}$

$\cos\left(\frac{1}{5}x\right)=-\frac{\sqrt{2}}{2}$

$\sqrt{x\cdot\sqrt[5]{x^{2}\cdot\sqrt[3]{x^{7}\cdot\sqrt{x^{4}}}}}$

$\lim_{x\to0}\left(x\cos\left(3x\right)\right)$