Answer 1

Let the G.P. be a, ar, ar², ar³, …

According to the given condition,

a + ar + ar² = 16 and ar³ + ar⁴ + ar⁵ = 128

⇒ a (1 + r + r²) = 16 … (1)

ar³(1 + r + r²) = 128 … (2)

Dividing equation (2) by (1), we obtain