Given GP is ….
The given GP is of the form, a, ar, ar2, ar3….
Where r is the common ratio.
The first term in the given GP,
The second term in GP,
Now, the common ratio,
Let us consider -128 as the nth term of the GP.
Now, nth term of GP is, an = arn – 1
n – 1
2)n = 1024 = (-2)10
n = 10
So, -128 is the 10th term in GP.