Q1. [1]
If the sum of first $m$ terms of an AP is $2m^2 + 3m$, then its second term is:
- A $10$
- B $9$
- C $12$
- D $4$
Previously asked in CBSE board exam
2025 30/1/1 Q11
Generated by claude-sonnet-4-6 · 2026-06-15 10:30 · grounding rag
Model Answer
$S_m = 2m^2 + 3m$
$a_2 = S_2 - S_1 = (2(4)+3(2)) - (2(1)+3(1)) = 14 - 5 = \mathbf{9}$
Answer: (B) 9
Explanation
The nth term of an AP can be found using $a_n = S_n - S_{n-1}$. Substitute $m=2$ and $m=1$ into the given sum formula and subtract. Avoid confusing $S_n$ (sum) with $a_n$ (term) — a common mistake.
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