Here is the problem:
y



−12y


+32y

=21ex
y(0)=27

y

(0)=21

y


(0)=25
Y(x) = ??
I used the method of undetermined coefficients and my answer is:
(71/3)+(8/3)e^(4x)+(-1/3)e^(8x)+e^x
But the online-homework wouldn't accept it and says it's incorrect...
Here is what I did:
Yp(x) = (C1) + (C2)e^(4x) + (C3)e^(8x) + e^x
Y'p(x) = 4(C2)e^(4x) + 8(C3)e^(8x) + e^x
Y''p(x) = 8(C2)e^(4x)+64(C3)e^(8x) + e^x
then after plug in and used the given initial values I got:
(C1) + (C2) + (C3) + 1 = 27
4(C2) + 8(C3) + 1 = 21
8(C2) + 64(C3) + 1 = 25
so C1 = 71/3
C2 = 8/3
C3 = -1/3
Please help!!!
Thank You!!