第一題：（4x+3）（5-x）=0
(4x+3)(x-5)=0
(x+3/4)(x-5)=0
x=-3/4,x=5
2t：(x-1)^2+2x(x-1)
是不是漏了=0
(x-1)(x-1+2x)=0
(x-1)(3x-1)=0
x=1,x=1/3
3t:2x^2-4x-5=0
x^2-2x=5/2
x^2-2x+1=5/2+1
(x-1)^2=7/2=[±√(7/2)]^2=(±√14/2)^2
x-1=±√14/2
x=(2+√14)/2,x=(2-√14)/2
4t:-3x^2-4x+4=0
3x^2+4x-4=0
3x^2-2x+6x-4=0
x(3x-2)+2(3x-2)=0
(3x-2)(x+2)=0
x=2/3,x=-2
5t:3x(x-1)=2-2x
3x(x-1)+2x-2=0
3x(x-1)+2(x-1)=0
(x-1)(3x+2)=0
x=1,x=-2/3
6t:(x-1)(x+2)=70
x^2+x-2-70=0
x^2+x-72=0
x^2+9x-8x-72=0
x(x+9)-8(x+9)=0
(x+9)(x-8)=0
x=-9,x=8
7t:x(x+6)=7
x^2+6x-7=0
x^2-x+7x-7=0
x(x-1)+7(x-1)=0
(x-1)(x+7)=0
x=1,x=-7
8t:(3-x)^2+x^2=9
x^2-6x+9+x^2=9
2x^2-6x=0
2x(x-3)=0
x=0,x=3