$\frac{dx}{dy}=\frac{x^3y}{\sqrt{1+y^2}}$

$-\:\left\{-20\:-\:-4\:-\:\left[-8\:+\:\left(+12\:-6\:-2\right)\:+2\:+3\right]\right\}-\:-4\:-\:\left[-8\:+\:\left(+12\:\:-2\right)\:+2\:+3\right]$

$\left(-10+3.4\right).\left(-1-1\right)+15:\:\left(-3\right)$

$\left(-11x^6y^2\right)\left(-5mxy^7\right)$

$\lim_{x\to-\infty}\left(x\left(\arctan\left(x\right)+\arccos\left(\frac{1}{x}\right)\right)\right)$

$\cos^2\left(\frac{\pi}{4}-x\right)-\sin^2\left(\frac{\pi}{4}-x\right)$

$\sin\left(4x\right)\sin\left(2x\right)$