Question

一元二次方程的解法 配方法

x²-4x-1=0

x²-7=3x

2x²-4x-1=0

三分之一x²-2x-2=0

0.2x²-0.6x=1
过程

Answer 1

x²-4x-1=0
x²-4x+4-5=0
(x-2)^2=5
x-2=√5或x-2=-√5
x=2+√5或x=2-√5

x²-7=3x
x²-3x=7
x²-3x+(3/2)^2=7+(3/2)^2
(x-3/2)^2=37/4
x-3/2=√37/2或x-3/2=-√37/2
x=3/2+√37/2或x=3/2-√37/2

2x²-4x-1=0
x²-2x=1/2
x²-2x+1=1/2+1
(x-1)^2=3/2
x-1=√6/2或x-1=-√6/2
x=1+√6/2或x=1-√6/2

三分之一x²-2x-2=0
x²-6x=6
x²-6x+9=6+9
(x-3)^2=15
x-3=√15或x-3=-√15
x=3+√15或x=3-√15

0.2x²-0.6x=1
x²-3x=5
x²-3x+(3/2)^2=5+(3/2)^2
(x-3/2)^2=29/4
x-3/2=√29/2或x-3/2=-√29/2
x=3/2+√29/2或x=3/2-√29/2

Answer 2

题目不明确，无法解答

Answer 3

数学