giải giúp mình luôn câu: 4x2- 4xy + y2 -8x +4y
x3-3x2+3x-1=x3-3x2+3x-13=(x-1)(x2+x+1)+3(x2-x)
x3-3x2+3x-1
=(x3-1) -(3x2-3x)
=(x-1)x(x2-x+1)-3xx(x-1)
=(x-1)x(x2-x-3x+1)
=(x-1)x(x2-4x+1)
4x2-4xy+y2-8x+4y
=4x2-8x+4+ y2+4y-4
=(2x-2)2-(y-2)2
=(2x-2+y-2)x(2x-2-y+2)
=(2x+y-4)x(2x-y)