已知x2-5x-16=0,求(x-1)(2x-1)-(x+1)2+1的值.
问题描述:
已知x2-5x-16=0,求(x-1)(2x-1)-(x+1)2+1的值.
答
(x-1)(2x-1)-(x+1)2+1
=2x2-3x+1-x2-2x-1+1
=x2-5x+1
∵x2-5x-16=0,
∴x2-5x=16,
∴原式=16+1=17.