.用配方法解下列方程:(1) x2+4x=2;   (2)x2+3x+1=0.(3)4x^2 -12x -1=0

来源:学生作业帮助网 编辑:六六作业网 时间:2024/12/26 05:19:52
.用配方法解下列方程:(1)x2+4x=2;  (2)x2+3x+1=0.(3)4x^2-12x-1=0.用配方法解下列方程:(1)x2+4x=2;  (2)x2+3x+1=0.(3)4x^2-12x

.用配方法解下列方程:(1) x2+4x=2;   (2)x2+3x+1=0.(3)4x^2 -12x -1=0
.用配方法解下列方程:(1) x2+4x=2;   (2)x2+3x+1=0.(3)4x^2 -12x -1=0

.用配方法解下列方程:(1) x2+4x=2;   (2)x2+3x+1=0.(3)4x^2 -12x -1=0
(1) x2+4x=2
∵ (x+2)^2=6
∴ x+2 =±√6
x =-2±√6
 (2)x2+3x+1=0.
(x+3/2)^2 =5/4
∴ x+3/2 =±√5 /2
x = (-3±√5)/2
(3)4x^2 -12x -1=0
4(x-3/2)^2 =10
(x-3/2)^2 =10/4
∴ x-3/2 =±√10 /2
x = (3±√10)/2