পঞ্চম পদ, ar⁴ = 2√3/9 --- (1)
দশম পদ, ar⁹ = 8√2/81 --- (2)
∴ r^{10 - 5} = (8√2/81) ÷ (2√3/9) = √(2/3)⁵
r = √2/√3
সমীকরণ (1) হতে, a = (2√3/9)/(√2/√3)⁴ = √3/2
এখন,ar² = √3/2 × (√2/√3)² = 1/√3