（6x-6y）²-3(x-y)+(6y-6x)²+（7y-7x）
=36(x-y)²-3(x-y)+36(x-y)²-7(x-y)
=(x-y)(36(x-y)-3+36(x-y)-7)
=(x-y)(72(x-y)-10)
=(x-y)(72x-72y-10)