CA Foundation · Quantitative Aptitude · Sequence and Series
Which of the following is the general term (nth term) of the sequence 2, 5, 10, 17, 26, ...?
The general term is n² + 1. Each term exceeds a perfect square by one: 1+1=2, 4+1=5, 9+1=10, 16+1=17 and 25+1=26. Hence the nth term equals n squared plus one, which matches every given term of the sequence.
- An² + 1Correct
- Bn² + 2
- C2n + 1
- Dn² + n
Explanation
Terms are 1+1, 4+1, 9+1, 16+1, 25+1, so the nth term is n² + 1. Check: n=5 gives 26. The option n² + 2 gives 3 for n=1, which does not match the first term 2.
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