Question

if fourth term of the gp is 40 and 10th term is 2560. find gp​

Answer 1

It's 5,10,20,40,80,160,320,640,1280,2560

Answer 2

a4 = 40, a10= 2560

formula an = a×r^(n-1)

a4= a×r^(4-1)

a4= a×r³ = 40......(1)

a10 = a×r^(10-1)

a10= a×r^9 = 2560......(2)

divide (2) by (1)

r^9/r³ = 2560/40

r³ = 64

r³ = 4³

r= 4

put this value in (1)

we get:-

a= 5/8

so, GP is

5/8,5/2,10,40,.......