(5x-2)²=9(x+3)²配方法解方程
1个回答

配方法:

(5x-2)² = 9(x+3)²

25x² - 20x + 4 = 9x² + 54x + 81

16x² - 74x = 77

x² - 37/8 x = 77/16

x² - 37/8 x + (37/16)² = 77/16 + (37/16)²

(x - 37/16)² = 2601 / 16²

x - 37/16 = ± 51/16

x₁ = 11/2 ,x₂ = - 7/8

这道题用直接开方法比较简单

(5x-2)² = 9(x+3)²

5x-2 = 3(x+3) 或 5x-2 = - 3(x+3)

x₁ = 11/2 ,x₂ = - 7/8