已知x²-2x=1,求﹙x-1﹚﹙3x+1﹚-﹙x+1﹚²的值
问题描述:
已知x²-2x=1,求﹙x-1﹚﹙3x+1﹚-﹙x+1﹚²的值
答
x²-2x=1
x²-2x-1=0
﹙x-1﹚﹙3x+1﹚-﹙x+1﹚²
=3x²-2x-1-x²-2x-1
=2x²-4x-2
=2(x²-2x-1)
=0