$xy'+2y=4x^2,y\left(1\right)=2$

$x^2+6x+9-\left(x^2+4x+4\right)+\left(x+4\right)^2-\left(x+5\right)^2$

$x^2-x-8$

$\frac{dy}{dx}\left(9x^2-y^2=1\right)$

$\cos^3\left(x\right)+\cos\left(x\right).\sin^2\left(x\right)=0$

$\lim_{x\to-\infty}\left(\frac{4x^2+x^2+5}{3x^5+x^3-x}\right)$

$3\left(-4n+2\right)$