Discussion
Sum to \(n\) terms of an Arithmetic progression is \(2n^{2}+n\) then eighth term is
Answer: D
The eighth term is 31.
The \(n\)th term is the difference of consecutive sums:
\[ \begin{aligned} T_{8} &= S_{8} - S_{7} \\ &= (2 \cdot 64 + 8) - (2 \cdot 49 + 7) \\ &= 136 - 105 = 31 \end{aligned} \]
Check: \(S_{1} = 3\) and \(S_{2} = 10\), so the progression is 3, 7, 11, ... with common difference 4, and \(T_{8} = 3 + 7 \times 4 = 31\). 136 is \(S_{8}\), the sum of eight terms, not the eighth term.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development