X的三次方-X的两次方+X-1
X的方+4(XY-1)+4y方
x=1时 为0所以有因式x-1
x³-x²+x-1
=x²(x-1)+(x-1)
=(x²+1)(x-1)
x²+4xy-4+4y²
=x²+4xy+4y²-4
=(x+2y)²-4
=(x+2y+2)(x+2y-2)
1、
=x²﹙x-1﹚+x-1
=﹙x²+1﹚﹙x-1﹚
2、
=﹙x+2y﹚²-2²
=﹙x+2y+2﹚﹙x+2y-2﹚