x pangkat 2-x-30=0 cara melengkapkan kuadrat sempurna tolong ya everyone

Mencari akar" persamaan kuadrat dg melengkapkan kuadrat

x² - x - 30 = 0
x² - x = 30
x² - 2 . 1/2 x + (1/2)² = 30 + (1/2)²
(x - 1/2)² = 30 + 1/4
(x - 1/2)² = (120 + 1)/4
x - 1/2 = ± √(121/4)
x - 1/2 = ± 11/2
x = 1/2 ± 11/2

Akar" persamaan kuadrat x² - x + 30 = 0
x1 = 1/2 + 11/2 = 12/2 = 6
x2 = 1/2 - 11/2 = -10/2 = -5