Question

What is the 8th term of G.P 5,10,20 .......

Answer 1

a=5

r=10/5=2

T8=?

T8=ar^n-1

=5×2^8-1

=5×2^7

=5×128=640

Answer 2

Hi baby

In general, a geometric sequence is given by:

a,ar,ar2,⋯,arn−1

In the sequence 5,10,20,40,…

First term, a = 5

Common ratio, r = 105 = 2

Equate the term to be found with the nth term.

arn−1=1280

5×2n−1=1280

2n−1=12805

2n−1=256

2n−1=28

If the bases are same, then the powers must be equal.

⟹n−1=8

⟹n=8+1

⟹n=9

Therefore, 9thof the sequence is 1280.

Brainiest answer please.