Which term of the GP is -128?

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 n^th term of the GP.

Now, n^th term of GP is, a_n = ar^{n – 1}

^{n – 1}

2)ⁿ = 1024 = (-2)¹⁰

n = 10

So, -128 is the 10^th term in GP.