b5 = b3 * q²
q² = b5 ÷ b3
q² = 40 ÷ 10 = 4
q = 2
bn = b1 * qn-¹
b1 = bn ÷ qn-¹
b1 = b3 ÷ q³-¹
b1 = 10 ÷ 4 = 2,5.
b5 = b3 * q²
q² = b5 ÷ b3
q² = 40 ÷ 10 = 4
q = 2
bn = b1 * qn-¹
b1 = bn ÷ qn-¹
b1 = b3 ÷ q³-¹
b1 = 10 ÷ 4 = 2,5.