Question

解一元二次方程：3x²-6x=-3,4x²-121=0 3x（x-1)=2(x-1),(2x-1)²=(3-x)²

2(x+3)²=x²-9,5x(x-1)=2-2x
要过程

Answer 1

1) 3x²-6x=-3
x^2-2x+1=0
(x-1)^2=0
x=1

2)4x²-121=0=11^2
2x=+11或 -11
x=11/2 或-11/2

3)3x（x-1)=2(x-1)
3x^2-3x=2x-2
3x^2-5x+2=0
(3x-2)(x-1)=0
x=2/3或 x=1
4）(2x-1)²=(3-x)²
直接开方
2x-1=3-x或2x-1=x-3
得到x=4/3或-2

5）2(x+3)²=x²-9=（x+3)(x-3)
2(x+3)^2-（x+3)(x-3)=0
(x+3)(2x+6-x+3)=0
x =-3或-9

6）5x(x-1)=2-2x
5x^2-5x+2x-2=0
5x^2-3x-2=0
(5x+2)(x-1)=0
x=-2/5或1

Answer 2

1. x1=x2=1
2. x1=11/2; x2=-11/2
3. x1=1; x2=2/3
4. x1=-2; x2=4/3