Question

Determine an ap whose third term is 9 and sister term is subtracted from 8 we get 6

Answer 1

3rd term = a+(n-1)d

=>> a+(3-1)d = 9

=>> a+2d = 9

=>> a= 9-2d

sister term of 3rd term is 4th term therefore ,

4th term = a+(n-1)d

=>> a+(4-1)d -8 = 6

=>> a+3d-8=6

=>> a+3d=6+8

=>> a+3d =14

Substituting (a=9-2d )

=>> (9-2d)+3d = 14

=>> 9+d = 14

=>> d= 14-9

=>> d= 5

Substituting (d=5) in (a=9-2d)

=>> a=9-2(5) = 9-10

=>> a=-1

Hence A.P is -1,4,9,14,19,24,29,......