Asked by Lillian

The 9th term of an arithmetic sequence is 12 and the 17th term is 28, find the 4th term of the arithmetic sequences
Answered by Reiny
9th term = a+8d = 12
17th term= a+16d = 28
subtract them
8d = 16
d = 2

sub into a+8d = 12
a = -4

4th term = a+3d = -4 + 6 = 2