1.(4x+3)(5-x)=0
x1=-3/4,x=5
2.(x-1)^2+2x(x-1)=0
(x-1)(x-1+2x)=0
(x-1)(3x-1)=0
x1=1,x2=1/3
3.2x^2-4x-5=0
套万能公式
x1=(2+根下14)/2,x2=(2-根下14)/2
4.-3x^2-4x+4=0
十字相乘法
(-3x+2)(x+2)=0
x1=2/3,x2=-2
5.3x(x-1)=2-2x
3x(x-1)+2(x-1)=0
(x-1)(3x+2)=0
x1=1,x2=-2/3
6.(x-1)(x+2)=70
x^2+x-72=0
（x-8)(x+9)=0
x1=8,x2=-9
7.x(x+6)=7
x^2+6x-7=0
(x+7)(x-1)=0
x1=-7,x2=1
8.(3-x)^2+x^2=9
9-6x+x^2+x^2=9
2x^2-6x=0
2x(x-3)=0
x1=0,x2=3