(x-1)^2-(x-1)(x+5)=9（x-1）（x-1-x-5）=9-6（x-1）=9-2（x-1）=3x-1=-1.5x=1-1.5x=-0.5
(x-1)^2-(x-1)(x+5)=9x^2-2x+1-x^2-4x+5=9-6x=3x=-1/2
解：（x-1）*-6=9x-1=-1.5x=-1/2
x=3
