题目

若x-y=5,xy=6 则x²y-xy²=—————,2x²+2y²________

提问时间：2020-10-24

答案

若x-y=5,xy=6
则
x²y-xy²
=xy(x-y)
=6×5
=30;
2x²+2y²
=2(x²+y²)
=2[(x-y)²+2xy]
=2×(5²+2×6)
=2×(25+12)
=2×37
=74