- #1
CAF123
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Homework Statement
Find the general solution of the ODE $$ y'' + 16y = 64x \cos x.$$ If ## y(0)=1, y'(0) = 0##, what is the particular solution?
The Attempt at a Solution
I am confident I can tackle this question, I really just want to check that my particular integral form is correct. I originally said ##y_p(x) = x(C_1 \cos 4x + C_2 \sin 4x)(ax + b)##, where ##C_1, C_2, a,b ## are constants. However, when I do the first derivative and then the second derivative and then sub this into the ODE, I get two eqns with 4 unknowns. (The 4 unknowns being the constants). So then I tried combining the form so that there was only two constants. So I have either ##x[(C_1 \cos 4x + C_2 \sin 4x)(C_1 x + C_2)]## or ## x[(C_1 x +C_2)\cos 4x + (C_1x +C_2)\sin 4x]## Should I go with the second option?
Thanks