若x-y=5,xy=6 则x²y-xy²=—————,2x²+2y²________
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![若x-y=5,xy=6 则x²y-xy²=—————,2x²+2y²________](/uploads/image/z/2638490-50-0.jpg?t=%E8%8B%A5x-y%3D5%2Cxy%3D6+%E5%88%99x%26%23178%3By-xy%26%23178%3B%3D%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%2C2x%26%23178%3B%2B2y%26%23178%3B________)
若x-y=5,xy=6 则x²y-xy²=—————,2x²+2y²________
若x-y=5,xy=6 则x²y-xy²=—————,2x²+2y²________
若x-y=5,xy=6 则x²y-xy²=—————,2x²+2y²________
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
30 和 74
x²y-xy²=xy(x-y)=6*5=30
2x²+2y²=2x²+2y²-4xy+4xy=2(x-y)^2 +4xy=2*5^2 + 4*6=50 +24=74
x²y-xy²=xy(x-y)
2x²+2y²=2(x²+y²)
=2[(x-y)²+2xy]
这样代入就行了
答案是30,74