Which option gives the rule for an AP whose first term is 14 and common difference is \(-3\)?
Advertisement
Answer and explanation
Correct answer: \(a_n=17-3n\)
The nth term of an AP is \(a_n=a+(n-1)d\). Substituting \(a=14\) and \(d=-3\) gives \(a_n=14-3(n-1)=17-3n\). A rule containing \(n^2\) does not produce a constant difference. Exam tip: identify \(a\) and \(d\) first.
Frequently asked questions
What is the correct answer to this question?
\(a_n=17-3n\)
Why is this the correct answer?
The nth term of an AP is \(a_n=a+(n-1)d\). Substituting \(a=14\) and \(d=-3\) gives \(a_n=14-3(n-1)=17-3n\). A rule containing \(n^2\) does not produce a constant difference. Exam tip: identify \(a\) and \(d\) first.
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.
Advertisement