解：原式=（x-y)^6*[-(x-y)^9]*(x-y)^6*[-(x-y)^9] =（x-y)^30
[(x-y)³]²×[(y-x)³]³ =(x-y)的6次方×[-(x-y)的9次方]=-(x-y)的15次方
(x-y)45次方
