Question

solve (D2+9)y = cos2x
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Answer 1

Answer:

Ans is y=A cos3x+B sin3x+(1/5) cos2x

Step-by-step explanation:

D^2+9=cos2x

To find A. E

m^2+9=0, m=+3i, -3i

A. E y=A cos3x+B sin3x

To find P. I

y=1/(D^2+9) cos2x, on solving

y=1/(-2*2+9) cos2x=1/5cos2x

y=A.E+P.I

y=A cos3x+B sin3x+(1/5) cos2x