Sorry for this dumb questions! its that i am just trying to find multiple ways of solving problems: Basically i have(adsbygoogle = window.adsbygoogle || []).push({});

y'' + 9y' = 648sin(9 t) + 648cos(9 t)

i dont know how can you complexify this, would it be p(D)y=648exp(9t)?

if so, what part do i extract, the imaginary or real? because it has both....

i can solve this with uknown coefficients but i am trying to look for efficient ways of doing this.

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# Complexification of rsin(at)+rcos(at)

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