（x-1)(x-2)-3x(x-4)-2(x+2)(x-1)
问题描述：
（x-1)(x-2)-3x(x-4)-2(x+2)(x-1)
x=-2分之1
答
答：
(x-1)(x-2)-3x(x-4)-2(x+2)(x-1)
=(x-1)(x-2-2x-4)-3x(x-4)
=(x-1)(-x-6)-3x(x-4)
=-x^2-5x+6-3x^2+12x
=-4x^2+7x+6
=-4*(-1/2)^2+7*(-1/2)+6
=-1-7/2+6
=5-7/2
=3/2