Which of the following formulas defines an arithmetic progression (AP)?
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Answer and explanation
Correct answer: \(a_n=3n-5\)
For \(a_n=3n-5\), \(a_{n+1}-a_n=[3(n+1)-5]-(3n-5)=3\), which is constant for every \(n\). Hence it is an AP. For \(n^2+1\), the difference changes. Exam tip: check consecutive-term differences.
Frequently asked questions
What is the correct answer to this question?
\(a_n=3n-5\)
Why is this the correct answer?
For \(a_n=3n-5\), \(a_{n+1}-a_n=[3(n+1)-5]-(3n-5)=3\), which is constant for every \(n\). Hence it is an AP. For \(n^2+1\), the difference changes. Exam tip: check consecutive-term differences.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the $n$th term of an AP.
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