$\left(3+x\right)\left(3-y\right)-\left(3x-2y-xy\right)$

$\lim_{x\to-1}\left(\frac{y+1}{y^2+1}\right)$

$\int\frac{6x^2}{\left(36+x^2\right)^2}dx$

$y\left(1-x^2\right)\frac{dy}{dx}=4x\left(1-2y^2\right)$

$\frac{x^4-8x^3+3x+2}{x+2}$

$\left(16x^2-m^2-x\right)\left(6x^2+m^2x\right)$

$\int\cos^6\left(7x\right)\sin^8\left(7x\right)dx$