If the sum of first $n$ terms of an $A.P.$ is $c n^2$, then the sum of squares of these $n$ terms is
If the sum of first $n$ terms of an $A.P.$ is $c n^2$, then the sum of squares of these $n$ terms is
- [IIT 2009]
- A
$\frac{n\left(4 n^2-1\right) c^2}{6}$
- B
$\frac{n\left(4 n^2+1\right) c^2}{3}$
- C
$\frac{n\left(4 n^2-1\right) c^2}{3}$
- D
$\frac{n\left(4 n^2+1\right) c^2}{6}$
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