若xy=1,则(x+y)²-(x-y)²的值是( )

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(x+y)²-(x-y)²
=x²+2xy+y²-(x²-2xy+y²)
=x²+2xy+y²-x²+2xy-y²
=4xy
=4*1
=4

若xy=1,则(x+y)²-(x-y)²的值是( ) 若x² +xy+y² =14,x² -xy+y²=28求x+y的值若x²+xy+y²=14,x²-xy+y²=28,求x+y的值 1.若x+y=3,xy=1,求(x-y)²,x²+y²的值. 若x/y=2,求7x²-3xy+2y²/2x²-3xy+7y²的值答案是8/3 若x²-xy+y²=1,则x²+y²的取值范围.试卷上一道填空题, 已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值 1.已知3x²-xy+y²=10,-xy+4y²=4,则x²-y²的值若多项式x²-2xy+y²-x+y-1=0,求x-y的值. .已知xy=8满足x²y-xy²-x+y=56,求x²+y²的值 2.若x-3= x²+y²+4x-8y+20=0,求分式x²-y²/xy的值已知X²+XY=3,XY+Y²=2,则代数式X²+2xy的值为