The integrating factor of the differential equation $x\frac{dy}{dx}-2y=x^3$ is

$x^2$ $\frac{1}{x^2}$ $-x^2$ $\frac{-1}{x^2}$

$\frac{1}{x^2}$

$x\frac{dy}{dx}-2y=x^3$ $⇒\frac{dy}{dx}-\underbrace{\frac{2y}{x}}_p=\underbrace{x^2}_q$ Integrating factor = $e^{\int p\,dx}$ $⇒e^{\int\frac{-2}{x}dx}=e^{-2\log x}=e^{\log(1/x^2)}=\frac{1}{x^2}$