$5x^3+15x^2$

$\frac{dy}{dx}=3x^2+3x^2\cdot y^2$

$\int\left(\frac{x^2+2x+3}{x^2-3x+2}\right)\:dx$

$\int r^6\left(1+r^7\right)^5dx$

$\left(6x^2+5\right)^2$

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

$\lim_{x\to\infty}\left(\frac{7x^3-2x+2}{4x^4-3x^2+6x}\right)$