$\int x^3\cdot\frac{1}{\left(4+x^2\right)^{\frac{1}{2}}}dx$

$4m^2\left(x^4-y^4\right)+16m\left(x^4-y^4\right)$

$36x^2+36x+36y^2$

$\frac{9x^{-1}y^{-6}}{3x^{-2}y^{-9}}$

$\lim_{x\to0}\left(\frac{x^2}{2x-1}\right)$

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

$\frac{6x^3+23x^2+11x-5}{2x+3}$