Odpowiedź:
a₁ = 3
a₂ = x + 1
a₃ = x + 7
a₂² = a₁ * a₃
(x + 1)² = 3(x + 7)
x² + 2x + 1 = 3x + 21
x² + 2x - 3x + 1 - 21 = 0
x² - x - 20 = 0
a = 1 , b = - 1 , c = - 20
Δ = b² - 4ac = (-1)² - 4 * 1 * (- 20) = 1 + 80 = 81
x₁ = ( - b - √Δ)/2a = (1 - 9)/2 = - 8/2 = - 4
x₂ = (- b + √Δ)/2a = (1 + 9)/2 = 10/2 = 5
a₁ = 3
a₂ = x₁ + 1 = - 4 + 1 = - 3
a₃ = x₁ + 7 = - 4 + 7 = 3
lub
a₁ = 3
a₂ = x₂ + 1 = 5 + 1 = 6
a₃ = x₂ + 7 = 5 + 7 = 12
q₁ = a₂/a₁ = 3/(- 3) = - 3/3 = - 1
lub
q₂ = a₂/a₁ = 6/3 = 2
