已知x+y=3,xy=0.5,求(1)2x²y+2xy²的值;(2)x²+y²的值
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![已知x+y=3,xy=0.5,求(1)2x²y+2xy²的值;(2)x²+y²的值](/uploads/image/z/3911013-45-3.jpg?t=%E5%B7%B2%E7%9F%A5x%EF%BC%8By%EF%BC%9D3%2Cxy%EF%BC%9D0.5%2C%E6%B1%82%EF%BC%881%EF%BC%892x%26%23178%3By%EF%BC%8B2xy%26%23178%3B%E7%9A%84%E5%80%BC%EF%BC%9B%EF%BC%882%EF%BC%89x%26%23178%3B%EF%BC%8By%26%23178%3B%E7%9A%84%E5%80%BC)
已知x+y=3,xy=0.5,求(1)2x²y+2xy²的值;(2)x²+y²的值
已知x+y=3,xy=0.5,求(1)2x²y+2xy²的值;(2)x²+y²的值
已知x+y=3,xy=0.5,求(1)2x²y+2xy²的值;(2)x²+y²的值
(1)
2x²y+2xy²
=2xy(x+y)
=2*0.5*3
=3
(2)
x²+y²
=(x+y)²-2xy
=3²-2*0.5
=9-1
=8
2x²y+2xy²=2xy(x+y)=2X0.5X3=3
x²+y²=x²+2xy+y²-2xy=(x+y)2-2xy=3x3-1=8
(1)2x²y+2xy²=2xy(x+y)=2*0.5*3=3;
(2)x²+y²=(x+y)²-2xy=3²-2*0.5=8.
此题应用了乘法分配律、完全平方公式