已知x²-5x-7=0,求(x-1)(2x-1)-(x+1)²+1的值

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已知x²-5x-7=0,求(x-1)(2x-1)-(x+1)²+1的值

(x-1)(2x-1)-(x+1)²+1
=2x^2-3x+1-x^2-2x-1+1
=x^2-5x+1
=7+1
=8.

(x-1)(2x-1)-(x+1)²+1
=2x^2-3x+1-x^2-2x-1+1
=x^2-5x+1
=7+1
=8.