b₁ = 72 , b₃ = 2 , bₙ > → b₂>0
b₁ · b₃ = b₁ · (b₁q²) = (b₁ q)² , b₁q = b₂ → b₁ = b₃ = b²/₂
b₂ = + √b₁ · b₃ = √72 · 2 = √144 = 12 > 0
b₂ = 12
b₁ = 72 , b₃ = 2 , bₙ > → b₂>0
b₁ · b₃ = b₁ · (b₁q²) = (b₁ q)² , b₁q = b₂ → b₁ = b₃ = b²/₂
b₂ = + √b₁ · b₃ = √72 · 2 = √144 = 12 > 0
b₂ = 12