How do you integrate $e^{- x} cos (3 x) d x$ $e^(-x)cos(3x)dx$ ?

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Answer 1 · 2015-06-30T01:39:11

I found: $\frac{- e^{- x} cos (3 x) + 3 e^{- x} sin (3 x)}{10} + c$ $(-e^-xcos(3x)+3e^-xsin(3x))/10+c$

I used Integration by Parts (twice) and a little trick!
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