a) x² - 6x = 5x - 18
x² - 11x + 18 = 0
D = (-11)² - 4 * 1 * 18 = 121 - 72 = 49
x1 = (11 + √49) / 2 = (11 + 7) / 2 = 9
x2 = (11 - √49) / 2 = (11 - 7) / 2 = 2
б) 3x² - 4x + 3 = x² + x + 1
2x² - 5x + 2 = 0
D = (-5)² - 4 * 2 * 2 = 25 - 16 = 9
x1 = (5 + √9) / 4 = (5 + 3) / 4 = 2
x2 = (5 - √9) / 4 = (5 - 3) / 4 = 0.5