`Sigma_(r=1)^(50)(r^2)/(r^2+(11-r)^2)` is equal to ______. – InterviewSolution

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1.	`Sigma_(r=1)^(50)(r^2)/(r^2+(11-r)^2)` is equal to ______.
Answer» Correct Answer - 25 Let I-`sum_(r=1)^(50)r^(2)/(r^(2)+(11-r)^(2))` ….(1) Writing the series in reverse order, we get `I=sum_(r=1)^(50)((11-r)^(2))/(r^(2)+(11-r)^(2))` …(2) Adding (1) and (2), we get 2I=50 `rArrI=25`

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