若x满足x²-2x-1=0,求代数式(2x-1)²-x(x+4)+(x-2)(x+2)的值
2015-04-09
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(2x-1)^2-x(x+4)+(x-2)(x+2)
=4x²-4x+1-x²-4x+x²-4
=4x²-8x-3
=4x²-8x-4+1
=2(2x²-2x-1)+1
=2*0+1
=1
=4x²-4x+1-x²-4x+x²-4
=4x²-8x-3
=4x²-8x-4+1
=2(2x²-2x-1)+1
=2*0+1
=1
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