1. ## solve

y'''+y''+y'+y=x^2
thanks

2. Originally Posted by ceode
y'''+y''+y'+y=x^2
thanks
The roots of the characteristic equation are $-1,\pm i$, so the general solution for the homogeneus is:

$y_h(x)=C_1e^{-x}+C_2\cos x+C_3\sin x$

A particular solution for the complete has the form :

$y_p(x)=Ax^2+Bx+C$

Try it.

Fernando Revilla