(a+b)²-(3a-1)²
=﹙a+b+3a-1﹚﹙a+b-3a+1﹚
=﹙4a+b-1﹚﹙b-2a+1﹚
X^5(X-2)+X²(2-x)
=x²﹙x-2﹚﹙x³-1﹚
=x²﹙x-1﹚﹙x-2﹚﹙x²+x+1﹚
a²(x-y)²+2a(X-y)^3+(X-Y)^4
=﹙x-y﹚²[a²+2a﹙x-y﹚+﹙x-y﹚²]
=﹙x-y﹚²﹙x-y+a﹚²
(a+b)²-(3a-1)²
=﹙a+b+3a-1﹚﹙a+b-3a+1﹚
=﹙4a+b-1﹚﹙b-2a+1﹚
X^5(X-2)+X²(2-x)
=x²﹙x-2﹚﹙x³-1﹚
=x²﹙x-1﹚﹙x-2﹚﹙x²+x+1﹚
a²(x-y)²+2a(X-y)^3+(X-Y)^4
=﹙x-y﹚²[a²+2a﹙x-y﹚+﹙x-y﹚²]
=﹙x-y﹚²﹙x-y+a﹚²