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The sum of the `n` terms of the series `1+(1+3)+(1+3+5)+...` isA. `n^(2)`B. `{(n(n+1))/(2)}^(2)`C. `(n(n+1)(2n+1))/(6)`D. none of these |
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Answer» Correct Answer - C Let `a_(n)" be "n^(th)` term of the given series. Then, `a_(n)=1+3+5+ . . . +(2n-1)=n^(2)` `:." "` Sum of n-terms of the series `=underset(r=1)overset(n)suma_(r)=underset(r=1)overset(n)sumr^(2)=(n(n+1)(2n+1))/(6)` |
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