Find the sum of the following series to `n`term: `3xx1^2+5xx2^2+7xx3^2

1.	Find the sum of the following series to `n`term: `3xx1^2+5xx2^2+7xx3^2+`
Answer» Correct Answer - `(n(n+1)(3n^(2)+5n+1))/(6)` `T_(n)=("nth tem of "3,5,7,..) xx ("nth term of "1^(2),2^(2),3^(2),...)` `={3+(n-1)xx2}xx n^(2)=(2n+1)n^(2)=(2n^(3)+n^(2)).` `therefore S_(n)=2(sum_(k=1)^(n)k^(3))+(sum_(k=1)^(n)k^(2)).`

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