$\frac{\left(x^4-9x^2+x+2\right)}{x^2-9}$

$\left(5.x^3-2y\right)^3$

$\lim_{x\to0}\left(\frac{e^x-1-8x}{8x\left(e^x-1\right)}\right)$

$us=\frac{1}{2}kb$

$\int\left(x^3\sqrt{\left(a-x^2\right)}\right)dx$

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

$2\sin^2\theta+\cos\theta\:-2=-1$