Answers

2014-04-20T11:10:28+05:30
As the u know the last term in the K group is K(K+1)/2
the sum of terms till is given by
 \frac{ \frac{k(k+1)}{2}(\frac{k(k+1)}{2}+1) }{2}= \frac{\frac{k(k+1)}{2}\frac{k(k+1)+2}{2}}{2}
=  \frac{(k^2+k)^2+2(k^2+k)}{8}= \frac{k^4+k^2+2k^3+2k^2+2k}{8}= \frac{k^4+2k^3+3k^2+2k}{8}
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