A basic question from arithmetic progression chapter in which we have been asked to find the nth term of each of the following APs:(ii) 16,9, 2, -5, ….
(i) 5, 11, 17, 23,….
Book RS Aggarwal, class 10, Arithmetic Progression, chapter 5A, question no 5
i) AP is 16,9,2,−5,....
Here, first term =a=16
Common difference=d=9−16=−7
We know, nth term of AP
an=a+(n−1)d
=16+(n−1)(−7)
=16−7n+7
=(23−7n).
ii) Given AP is 5,11,17,23,....
Here, first term =a=5
Common difference =d=11−5=6
Now,
nth term an=a+(n−1)d
an=5+(n−1)6
=5+6n−6
=(6n−1).