$2.\frac{d^5}{dx^5}-7.\frac{d^4}{dx^4}+12\frac{d^3}{dx^3}+8\frac{d^2}{dx^2}=0$

$5x^2\:-\:y^2\:+\:4x^2\:-\:3y^2$

$\frac{3x^2}{x^3+1}$

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

$s^2-6\left(s^2+6\right)$

$\left(a^3-2\right)\left(a^3-4\right)$

$\frac{7x^2-31x+18}{x\left(x-3\right)^2}$