多项式x²-2xy+2y²+2y+5的最小值是______.
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多项式x²-2xy+2y²+2y+5的最小值是______.
多项式x²-2xy+2y²+2y+5的最小值是______.
多项式x²-2xy+2y²+2y+5的最小值是______.
=(x²-2xy+y²)+(y²+2y+1)+4
=(x-y)²+(y+1)²+4
最小值是4
76
x²-2xy+2y²+2y+5
=x²-2xy+y²+y²+2y+1+4
=(x-y)²+(y+1)²+4
所以当 x=y=-1时
最小值为4
4