已知x2-5x=3,求(x-1)(2x-1)-(x+1)2+1的值.

问题描述:

已知x2-5x=3,求(x-1)(2x-1)-(x+1)2+1的值.

(x-1)(2x-1)-(x+1)2+1
=2x2-x-2x+1-(x2+2x+1)+1
=2x2-x-2x+1-x2-2x-1+1
=x2-5x+1,
∵x2-5x=3,
∴原式=3+1=4.