解卖氏：
-2x²y³×(x-y)²×2/3·xy(x-y)³
=-2x²y³×2/3·xy×(x-y)²·(x-y)³
=-4/3·x³y⁴(x-y)⁵
原式
=2a²b³中空散×1/8·a²亏派b-1/4·a⁴b⁴
=1/4·a⁴b⁴-1/4·a⁴b⁴
=0