Երկրաչափական պրոգրեսիայի բանաձև՝

2, 4, 6, 8, 16…

q = b₂/b₁ = 4/2 = 2
b₂ = ⩲√b₁ * b₃
b_n = q * b₁^(n-1)
b₅ = 2 * 2⁴ = 2 * 16 = 32

2. b₂ = ⩲√b₁ * b₃
x = √1 * 9 = √9 = 3

4. b₂ = ⩲√b₁ * b₃
x = √1 * 4 = √4 = 2

6. b₂ = ⩲√b₁ * b₃
x = √2 * 8 = √16 = 8

8. b₂ = ⩲√b₁ * b₃
x = √3 * 27 = √81 = 9

10. b₂ = ⩲√b₁ * b₃
x = √4 * 64 = √256 = 16

102. b₅ = 7
b₁ * b₉ = ?

b5 = b₁ * q⁴
b1 * b9 = b₁ * b₁ * q⁸ = b₁² * q⁸ = (b₁ * q⁴) ² = 7² = 49

104. b₄ = 6
b₁ * b₇ = ?

b4 = b₁ * q³
b₁ * b₇ = b₁ * b₁ * q⁶ = b₁² * q⁶ = (b₁ * q³)² = 6² = 36

106. b₃ = 7
b₁ * b₅ = ?
b₃ = b₁ * q²
b₁ * b₅ = b₁ * b₁ * q⁴ = b₁² * q⁴ = (b₁ * q²)² = 7² = 49

114. q = 4/-4 = -1
b₂ = b₁ * q
-4 = b₁ * (-1)
b₁ = 1 * 4 = 4