the third of an arithmetic sequence is 14 and the ninth tern is -1. Find the first four terms of the sequence.

Answer 1

by definition:
a+2d = 14
a+8d = -1
subtract ...
6d = -15
d= -5/2

then
a+2(-5/2) = 14
a = 19

first 4 terms are
19, 33/2 , 14 , 23/2

Answer 2

a + 2d =14, a + 8d = -1. Solve simultaneously. . . .a =19 . .d =-5/2. .0. The sequence is . 19,16.5,14,11.5