已知x²-2x=1,求(x-1)(3x+1)-x(x+2)-1的值
4个回答
(x-1)(3x+1)-x(x+2)-1
=3x^2-2x-1-x^2-2x-1
=2x^2-4x-2
=2(x^2-2x)-2
=2-2
=0
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