配方法x^2+3x-2=0

Question

配方法 x^2+3x-2=0

Answer 1

x ² - 2 x - 5 = 0
x ² - 2 x + 1 - 1 - 5 = 0
（x - 1）² - 6 = 0
（x - 1）² = 6
x - 1 = ± √6
x = ± √6 + 1
x1 = √6 + 1
x2 = - √6 + 1
3 x ² + 2 x - 1 = 0
x ² + （2 / 3）x - 1 / 3 = 0
x ² + （2 / 3）x + （1 / 3）² - （1 / 3）² - 1 / 3 = 0
（x + 1 / 3）² - 1 / 9 - 1 / 3 = 0
（x + 1 / 3）² = 3 / 9 + 1 / 9
（x + 1 / 3）² = 4 / 9
x + 1 / 3 = ± 2 / 3
x = ± 2 / 3 - 1 / 3
x1 = 2 / 3 - 1 / 3 = 1 / 3
x2 = - 2 / 3 - 1 / 3 = - 1
打字不易,