已知x方-3x=4,求2(x-1)方-(x+1)(x-2)-3的值

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已知x方-3x=4,求2(x-1)方-(x+1)(x-2)-3的值
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已知x方-3x=4,求2(x-1)方-(x+1)(x-2)-3的值
已知x方-3x=4,求2(x-1)方-(x+1)(x-2)-3的值

已知x方-3x=4,求2(x-1)方-(x+1)(x-2)-3的值
x²-3x=4
2(x-1)方-(x+1)(x-2)-3
=2x²-4x+2-x²+x+2-3
=x²-3x+1
=4+1
=5

2(x-1)²-(x+1)(x-2)-3
=2(x²-2x+1)-(x²-x-2)-3
=x²-3x+1
因为x²-3x=4
则原式=4+1=5