3, x, x+6 are the first 3 terms of G.P
common ratio is x/3=x+6/x
so we cross multiply x×x=3×x+6
ײ= 3x+18 so we have x²-3x-18
(x-6)(x+3)=0
the possible value of x are 6 and -3
b) tenth term of the seauence
first of all the possible sequence are 3, 6, 12 and 3, -3, 3
but we need only the positive GP
so the common ratio of.the GP r is 6/3=2
the 10th term of a GP sequence is ar^10-1=ar^9
where a = first time
3×2^9=3×512=1536
the 10th term is 1536
