SOLUTION: If the first term of an arithmetic sequence is 4 and the third term is 18, what is the 23rd term? A.92 B.116 C.158 D.161

Algebra ->  Sequences-and-series -> SOLUTION: If the first term of an arithmetic sequence is 4 and the third term is 18, what is the 23rd term? A.92 B.116 C.158 D.161      Log On


   

Question 748283: If the first term of an arithmetic sequence is 4 and the third term is 18, what is the 23rd term?
A.92
B.116
C.158
D.161
Answer by reviewermath(1029) About Me  (Show Source):
You can put this solution on YOUR website!
The common difference is equal to d = %28a%5B3%5D+-+a%5B1%5D%29%2F%283+-+1%29 = %2818+-+4%29%2F2+ = 7. The nth term is a%5Bn%5D+ = a%5B1%5D+%2B+%28n+-+1%29d = 4+%2B+%28n-1%29%287%29+ = 7n+-+3.
The 23rd term is a%5B23%5D+=+7%2823%29+-+3+=+highlight%28158%29.