﹙2x+y﹚²-﹙x+2y﹚²
=[﹙2x+y﹚+﹙x+2y﹚][﹙2x+y﹚-﹙x+2y﹚]
=(3x+3y)(x-y)
=3(x+y)(x-y)
3ax²-3ay²
=3a(x²-y²)
=3a(x+y)(x-y)