SOLUTION: Find the twentieth term of the arithmetic sequence with a1 = 15 and d = 4.

Algebra ->  Sequences-and-series -> SOLUTION: Find the twentieth term of the arithmetic sequence with a1 = 15 and d = 4.      Log On


   

Question 745541: Find the twentieth term of the arithmetic sequence with a1 = 15 and d = 4.
Answer by tommyt3rd(5050) About Me  (Show Source):
You can put this solution on YOUR website!
For an arithmetic progression we use the formula:

a%5Bn%5D=a%5B1%5D%2B%28n-1%29%2Ad

n=20, a1=15, d=4


a%5B20%5D=15%2B%2820-1%29%2A4

a%5B20%5D=15%2B19%2A4

a%5B20%5D=91

:)