Question

The 4th term of a G. P. is 16 and the 7th term is 128. find the first term and common ratio of the series.​

Answer 1

Heya!!

Here's your answer!!

Let a be the first term and r be the common ratio of the given G.P.

therefore,

T4 = 16 and T7 = 128

=> ar³ = 16 .... (i)

and ar⁶ = 128. ....(ii)

Dividing equation (ii) by equation (i), we get

ar⁶/ar³ = 128/16

= r³ = 8

= r = 2

therefore,

From equation (i), a× 2³ = 16

= a= 16/8 = 2

a = 2,

r= 2.

Glad help you,

it's helps you,

thanks.