Q43 / 160 · AP EAMCET 2024 (19 May Shift 2) · Mathematics

$2.5+5.9+8.13+11.17+\ldots$ to 10 terms $=$

  • A
    3355
  • Correct answer
    B
    4555
  • C
    1375
  • D
    1380

Solution

Let $S=2.5+5.9+8.13+\ldots .+$ to 10 terms $\begin{aligned} & \Rightarrow S=\sum_{n=1}^{10}(3 n-1) \cdot(4 n+1)=12 \sum_{n=1}^{10} n^2-\sum_{n=1}^{10} n-\sum_{n=1}^{10} 1 \\ & \Rightarrow S=4620-55-10=4555 . \end{aligned}$

Hence, the correct answer is option: 'B'.

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