Question

write the nth term of ap -5,-1,3,7

Answer 1

Find the difference between each value. 7-3, 11-7 ...

For this series the difference is 4.

The nth term is then 4n + or - a constant.

The series is 3, 7, 11.. each of these is 1 below a multiple of 4.

4*1- 1 =3

4*2- 1=7 and so on.

So the nth term would be 4n-1

Answer 2

♠ ANSWER :

A. P. = - 5, - 1, 3, 7.

First term, a 1 = - 5,

Second term, a2 = -1

Common difference , d = a2 - a1 = - 1 - ( - 5)

d = - 1 +5 = 4

nth Term, An = a+ (n + 1 ) d

An = - 5 + ( n + 1 ) 4

An = - 5 + 4n + 4

⏺️An = 4n - 1 .