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

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.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

.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