Question

What is the 23rd term of the arithmetic sequence where a1 = 7 and a5 = 21?

Answer 1

the equation for an arithmetic sequence is:

an = a1 + (n – 1)d

Answer 2

First we'll have to solve for d, since we don't know what the distance each term is added/subtracted. This case added.

Answer 3

so, a(5)=7+(5-1)d where a(5) = 21

21=7+(5-1)d

just solve for d and then use the arithmetic sequence equation to find the 23rd term :)

Answer 4

thank you