When you substitute y''p and yp into the equation, where does the: 4Ccos(2x) and -4Dsin(2x) come from? While you have 10 different trig functions from the substitution, there should only have been 8 trig finctions from the substitution.... y'' = -9Asin(3x) - 9Bcos(3x) - 4Csin(

When you substitute y''p and yp into the equation, where does the:

4Ccos(2x) and -4Dsin(2x) come from?

While you have 10 different trig functions from the substitution, there should only have been 8 trig finctions from the substitution....

y'' = -9Asin(3x) - 9Bcos(3x) - 4Csin(2x) - 4Dcos(2x) --> that's 4

and 4y = 4(Asin(3x) + Bcos(3x) +Csin(2x) + Dcos(2x)) --> that's the other 4.

Where does the 4Ccos(2x) and -4Dsin(2x) come from in the multiplication?