The 9th term of an arithmetic sequence is 12 and the 17th term is 28, find the 4th term of the arithmetic sequences

1 answer

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