AP EAMCET · Maths · Sequences and Series
\(2.5+5.9+8.13+11.17+\ldots\) to 10 terms \(=\)
- A 3355
- B 4555
- C 1375
- D 1380
Answer & Solution
Correct Answer
(B) 4555
Step-by-step Solution
Detailed explanation
Let \(S=2.5+5.9+8.13+\ldots .+\) to 10 terms \(\begin{aligned} & \Rightarrow S=\sum_{n=1}^{10}(3 n-1) \cdot(4 n+1)=12 \sum_{n=1}^{10} n^2-\sum_{n=1}^{10} n-\sum_{n=1}^{10} 1 \\ & \Rightarrow S=4620-55-10=4555 . \end{aligned}\)
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