✔ 最佳答案
Method 1 : completing square
x² - 10x + 34 = 0
x² - 10x = -34
x² - 2(5)x + 5² = -34 + 5²
(x - 5)² = -9
x - 5 = √(-9) or x - 5 = -√(-9)
x - 5 = 3i or x - 5 = -3i ...... where i = √(-1)
x = 5 + 3i or x = 5 - 3i
Method 2 : using the formula x = [-b ± √(b² - 4ac)] / (2a)
x² - 10x + 34 = 0
x = {-(-10) ± √[(-10)² - 4(1)(34)]} / 2
x = [10 ± √(100 - 136)] / 2
x = [10 ± √(-36)]/2
x = [10 ± 6i]/2
x = 5 + 3i or x = 5 - 3i