2(x - 4) - x² + 3x = ( x + 1)(x -6)
2x - 8 - x² + 3x = x² - 6x + x - 6
- x² + 5x - 8 = x² - 5x - 6
- x² + 5x - 8 - x² + 5x + 6 = 0
- 2x² + 10x - 2 = 0
2x² - 10x + 2 = 0
D = b² - 4ac = ( - 10)² - 4 × 2 × 2 = 100 - 16 = 84
x₁ = 10 + √84 / 4
x₂ = 10 - √84 / 4