已知X2-5X-14=0求(x-1)×(2x-1)-(x+1)2+1的值
问题描述:
已知X2-5X-14=0求(x-1)×(2x-1)-(x+1)2+1的值
答
x²-5x-14=0
则:x²-5x=14
原式=2x²-3x+1-(x²+2x+1)+1
=x²-5x+1
=14+1
=15