jawabin ya penting banget

Persamaan Kuadrat
SMP Kelas VIII

2x² + 5x - 12 = (2x - 3)²
2x² + 5x - 12 = 4x² - 12x + 9
4x² - 2x² - 12x - 5x + 9 + 12 = 0
2x² - 17x + 21 = 0
(2x - 3)(x - 7) = 0

2x - 3 = 0
2x = 3
x = 3/2

x - 7 = 0
x = 7

x1 < x2
x1 = 3/2
x2 = 7

x2 - x1 = 7 - 3/2
             = 14/2 - 3/2
             = 11/2
             = 5 1/2 [B]

2x² + 5x - 12 = 4x² - 12x + 9
= (4x² - 2x²) - (12x + 5x) + (9 + 12)
= 2x² - 17x + 21
= (2x - 3) (x - 7)

2x - 3 = 0         x - 7 = 0
2x = 3              x₂ = 7
x₁ = ³/₂

x₂ - x₁ = 7 - ³/₂
            = ¹⁴/₂ - ³/₂
            = ¹¹/₂
            = 5 ¹/₂          Jawaban B