Mathematica solution with an imaginary part

ehrenfest · Mar 31, 2008

Can someone please explain why the result of the following has an imaginary part when I put it into mathematica 6.0?

Code:

Sum[Sin[n 6]/2^n, {n, 1, Infinity}]

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DeepakS · Mar 31, 2008

Because

Code:

Sin[n 6] / 2^n

is

Code:

2^-n * Sin[n 6]

Crosson · Apr 1, 2008

Wrap it in a full simplify command:

Code:

FullSimplify[Sum[Sin[n 6]/2^n, {n, 1, Infinity}]]

ehrenfest · Apr 1, 2008

DeepakS said:
Because
Code:
Sin[n 6] / 2^n
is
Code:
2^-n * Sin[n 6]

So what?

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