a(x-y)^2n-b(y-x)^2n+1
=a(y-x)^2n-b(y-x)^2n+1
=(y-x)^2n*(a-by+bx)
（a-b）²（a＋b）³-（b-a）²（b＋a）²
=(a-b)²(a+b)²(a+b-1)
2（a-b）²-a＋b
=(a-b)(2a-2b-1)
-x²（m-n）^5-xy（n-m）³
=-x²(m-n)^5+xy(m-n)³
=-x(m-n)³[x(m-n)²-y]
=-x(m-n)³(xm²-2mnx+xn²-y)
35ab（x-y）²-25a²b²（y-x）²＋10ab³（y-x）³
=5ab(x-y)²(7-5ab-2bx+2by)