一元二次方程分解因式法 1. 4(x+2)²=9(x-1)² 2. x²-2x-3=0 3. (2x-1)²-4(2x-1)=12 越

第3题的(2x-1)^2-4(2x-1)-12=0怎么变成[(2x-1)-6][(2x-1)+2]=0的?
2024-12-26 23:57:36
推荐回答(2个)
回答1:

1.
4(x+2)²=9(x-1)²
[2(x+2)+3(x-1)][2(x+2)-3(x-1)]=0
(5x+1)(7-x)=0
x=-1/5或x=7

2.
x²-2x-3=0
(x-3)(x+1)=0
x=3或x=-1

3.
(2x-1)²-4(2x-1)=12
(2x-1)^2-4(2x-1)-12=0
[(2x-1)-6][(2x-1)+2]=0
(2x-7)(2x+1)=0
x=7/2或x=-1/2

回答2:

1. (2x+4)²-(3x-3)²=0
(2x+4+3x-3)(2x+4-3x+3)=0
x=-1/5或x=7
2.(x-3)(x+1)=0
x=3或x=-1
3.(2x-1)²4(2x-1)-12=0
(2x-1-6)(2x-1+2)=0
x=7/2或x=-1/2