$\frac{2x^5-4x^4}{x^2+1}$

$\left(\frac{2x^3}{3}-\frac{3}{2}x^4\right)\left(\frac{2x^3}{3}+\frac{3}{2}x^4\right)$

$\frac{dy}{dx}\left(arctan\left(\frac{x}{2}\right)+arctan\left(\frac{2}{x}\right)\right)$

$\frac{tan\left(y\right)\left(tan\left(x\right)+cot\left(y\right)\right)}{tan\left(x\right)}=tan\left(y\right)+cot\left(x\right)$

$\left(\frac{3x^2}{x-1}\right)-\left(\frac{3x^2}{x+1}\right)$

$-\frac{3}{5}y-\frac{1}{7}y=910$

$2x^2+8x+1=0$