Given: 5th term of a GP is 2.
To find: the product of its first nine terms.
First term is denoted by a, the common ratio is denote by r.
∴ ar4 = 2
We have to find the value of: a × ar1 × ar2 × ar3 × … × ar8
= a9r1 + 2 + 3 + 4 + … + 8
= a9r36
= (ar4)9
= (2)9
= 512 .