FP2 edexcel 2nd order DE

just to confirm. If the roots of auxiliary equation are 1±3i, i.e, CF= e^x (cos 3x +sin 3x) and let say the right hand side of the differential equation is 5 cos 3x, we then need to try PI in a form of (A cos 3x + B sin 3x) right?

If however, the roots of AE are ±3i and RHS of the DE is the same then PI is in the form (Axcos3x + Bx sin 3x) right?