pv∫∞−∞x(x2+4)(x2+2x+2)dx
I get an answer of −π5 but wolframalpha disagrees by a factor of 2 (−π10):
http://www.wolframalpha.com/input/?i=integration+%28z%2F%28%28z^2%2B4%29%28z^2%2B2z%2B2%29%29%29++from+-+infinity+to+infinity
I cannot spot the error.
I get these residues:
Res(−1+i)=1+3i20
Res(2i)=−2−i40
which I add up and multiply by 2πi.
What am I doing wrong?
Answer
Res(2i)=x(x+2i)(x2+2x+2)|x=2i=2i4i(4i−2)=14(−1+2i)=−1−2i20
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