Schoolcrop

(Q2).Which term of the GP : 2, 2√2, 4 ..... is 128 ?

Here a = , r =

√2

= √

Let 128 be the n^th term of the GP

Then a_n = a.r^n-1 =

.(√)^n-1 =

(√)^n-1 =

()^{n-1
2} = ⁶

⇒

n-

=

∴ n = .

Hence 128 is the ^th term of the GP