# Please, can anybody help me to find the answer of this integration.

Posted 9 years ago
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 Integrate[(x - Subscript[x, i])^2 (x - Subscript[x, i + 1])^2, {x, Subscript[x, i - 1], Subscript[x, i + 1]}] Please i Need help to get this answer, i'll be very thankful.the answer is: -1/30 (Subscript[x,i-1]-Subscript[x,i+1])^3 (6(Subscript[x,i-1])^2+10(Subscript[x,i])^2-5(Subscript[x,i])(Subscript[x,i+1])+(Subscript[x,i+1])^2-15Subscript[x,i-1]Subscript[x,i]+3Subscript[x,i-1]Subscript[x,i+1])  Attachments:
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Posted 9 years ago
 Hi,... and one might add that the integration itself works perfectly if it is done in a clean way: Clear[x, a, b, c]; Integrate[(x - a)^2 (x - c)^2, {x, b, c}] /. {a -> Subscript[x, i], b -> Subscript[x, i - 1], c -> Subscript[x, i + 1]} @Marco: Thanks for this interesting link!Henrik
Posted 9 years ago
 That is really grateful Henrik Thanks a lot
Posted 9 years ago
 Hi,the issue is how Mathematica handles indices. This might be useful:http://community.wolfram.com/groups/-/m/t/272608Hope this helps, M.