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`sum_(r=1)^(n) r^(2)-sum_(r=1)^(n) sum_(r=1)^(n) ` is equal to |
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Answer» Correct Answer - C We have, `underset(r=1)overset(n)sumr^(2)-underset(r=1)overset(n)sumunderset(r=1)overset(m)sumr` `=underset(r=1)overset(n)sumr^(2)-underset(m=1)overset(n)sum(m(m+1))/(2)` `=underset(r=1)overset(n)sumr^(2)-(1)/(2)underset(m=1)overset(n)summ^(2)-(1)/(2)underset(m=1)overset(n)summ` `(1)/(2)underset(r=1)overset(n)sumr^(2)-(1)/(2)underset(r=1)overset(n)sumr=(1)/(2){underset(r=1)overset(n)sumr^(2)-underset(r=1)overset(n)sumr}` |
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