$\frac{\left(-9\right)+\left(-3\right)}{6}$

$12:-2$

$\frac{4x^2-8x+4}{x^2-1}$

$6x^2+2xy-20y^2+10x-68y-56$

$\frac{\left(3.542\cdot10^{-6}\right)^9}{\left(5.05\cdot10^4\right)^{12}}$

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

$\int_1^{\infty}\left(\frac{1}{x^2+2x}\right)dx$