5/12[-4/3(x-y)的三次方](x+y）的平方（-x-y）的三次方（y-x）的二次方
＝(-5/9)×(x-y)³×(x+y)²×[-(x+y)³]×(x-y)²
＝(5/9)×(x-y)的5次方×(x+y)的5次方
＝(5/9)×(x²-y²)的5次方