A) 1240
B) 1860
C) 660
D) 620
Correct Answer: D
Solution :
\[Sum=\sum\limits_{n=1}^{15}{\frac{{{1}^{3}}+{{2}^{3}}+....{{n}^{3}}}{1+2+3+....+n}-\frac{1}{2}.\frac{15.16}{2}}\] \[=\sum\limits_{n=1}^{15}{\frac{n(n+1)}{2}}-60\] \[=\sum\limits_{n=1}^{15}{\frac{n(n+1)(n+2-(n-1))}{6}}-60\] \[=\frac{15.16.17}{6}-60=620\]You need to login to perform this action.
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