题目内容
先化简,再求值:(x-1)2+(x-3)(x+3)+(x-3)(x-1),其中x2-2x=2.
(x-1)2+(x-3)(x+3)+(x-3)(x-1)
=x2-2x+1+x2-9+x2-4x+3
=3x2-6x-5
=3(x2-2x)-5,
∵x2-2x=2,
∴原式=3×2-5=1.
=x2-2x+1+x2-9+x2-4x+3
=3x2-6x-5
=3(x2-2x)-5,
∵x2-2x=2,
∴原式=3×2-5=1.
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