sum of an infinite gp is 57 and sum of their cube is 9747 find the gp

let the first term of the GP be a and the common ratio be r where -1<r<1

the GP is

therefore the sum of the infinite terms of the GP is

if taking the cube of each terms the new GP is

therefore the sum of their cube is

taking the cube of the (1) : ........(3)

substituting the value of a in terms of r in (2),

therefore r=3/2 or r=2/3 since r<1.

r=2/3

substitute in equation (1):

thus the first term of the GP is 19 and the common ratio is 2/3.

the GP is

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