The equation which I have is:

d2y/dx2 - dy/dx - 2y = 2cos(2x).

I know that I should find the Auxiliary equation, which in this case would be:

m^2 - m - 2 = 0

which would generate (m+2)(m-1)=0, giving the equation:

Ae^1 + Be^-2. The problem I have is finding the complimentary function, as I dont know what to start with. Any help is appreciated, and if possible find general solution. Thanks