A) 8840
B) 8440
C) 8540
D) 8450
E) 8000
Correct Answer: B
Solution :
\[{{15}^{2}}+{{16}^{2}}+{{17}^{2}}......+{{30}^{2}}\] \[={{1}^{2}}+{{2}^{2}}+...+{{30}^{2}}-({{1}^{2}}+{{2}^{2}}+....+{{14}^{2}})\] \[=\frac{30(31)(61)}{6}-\frac{14(15)(29)}{6}\] \[=\frac{56730-6090}{6}=8440\]You need to login to perform this action.
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