发布网友 发布时间:2024-10-01 02:09
我来回答
共2个回答
热心网友 时间:2024-10-07 09:14
原式=[(x²+y²)/xy-x²/(xy+y²)-y²/(x²+xy)]÷3/xy=[(x²+y²)(x+y)-x³-y³]/xy(x+y) ·xy/3=(xy²+x²y)/3(x+y)=xy/3