kuadrat sempurna x2-2x-4=0

x² - 2x = 4
x² - 2x + 4 = 4 + 4
(x - 2)² = 8
x - 2 = √8
x = 2 ± √8
x1 = 2 + √8 = 2 + 2√2
x2 = 2 - √8 = 2 - 2√2