4xy-[(x²+5xy-y²)-(x²+3xy-2y²)],其中x=2,y=-1求值与化简

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4xy-[(x²+5xy-y²)-(x²+3xy-2y²)],其中x=2,y=-1求值与化简
4xy-[(x²+5xy-y²)-(x²+3xy-2y²)],其中x=2,y=-1求值与化简

4xy-[(x²+5xy-y²)-(x²+3xy-2y²)],其中x=2,y=-1求值与化简
4xy-[(x²+5xy-y²)-(x²+3xy-2y²)]
=4xy-x²-5xy+y²+x²+3xy-2y²
=2xy-y²
=-2x1-(-1)²
=-2-1
=-3