Question

2X2-3X-1=0用配方法解方程,怎么解??

Answer 1

题目应该是：2x² - 3x - 1 = 0 用配方法解方程

2x² - 3x - 1 = 0
x² - 3x/2 - 1/2 = 0
x² - 3x/2 + (3/4)² =1/2 +(3/4)²
x² - 3x/2 + (3/4)² = 17/16
(x -3/4)² = 17 / 16
x -3/4 = ±√17 / 4
x = 3/4 ± √17 / 4
或
x = (3 ± √17) / 4

Answer 2

2x^2-3x-1=0
x^2-1.5x-0.5=0
x^2-1.5x=0.5
x^2-1.5x+0.5625=1.0625
(x-0.75)^2=1.0625
x-0.75=±(√17)/2
x=±(√17)/2+0.75

Answer 3

三楼的回答，你仔细算好了吗？
1/2+9/16等于27/16吗？
你自已重新算算，别误导提问者。

Answer 4

2x^2-3x-1=0
x^2-(3/2)x=1/2
x^2-(3/2)x + (3/4)^2 =1/2+9/16
( x^2-3/4)^2 =27/16
x^-3/4=±√27/16(即±3√3/4)
∴ x=（3√3+3）/4 或x=（3-3√3）/4

Answer 5

(2X-1)(X+1)=0