MCQ
${11^3} + {12^3} + .... + {20^3}$
  • A
    Is divisible by $5$
  • Is an odd integer divisible by $5$
  • C
    Is an even integer which is not divisible by $5$
  • D
    Is an odd integer which is not divisible by $5$

Answer

Correct option: B.
Is an odd integer divisible by $5$
b
(b) $\sum\limits_{n = 1}^{20} {({n^3})} - \sum\limits_{n = 1}^{10} {({n^3})} $

$= \left[ {\frac{{n(n + 1)}}{2}} \right]_{n = 20}^2 - \left[ {\frac{{n(n + 1)}}{2}} \right]_{n = 10}^2$

$= 44100 -3025 = 41075.$

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