SOLVE (D^2-DD'-2D'^2)z = (2x^2+xy-2y^2)sin(xy) - cos(xy) where D & D' are partial derivatives of z w.r.t x & y respectively.
I was able to solve complementary function easily. But I am unable to get particular integral. I used the general method where I divided f(D,D') into factors & substituted y=x+c first. Now this integral has gotten huge & I am unable to solve this. Please suggest me an easy method to find particular integral.