已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)的值.
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![已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)的值.](/uploads/image/z/2603629-37-9.jpg?t=%E5%B7%B2%E7%9F%A5xy%3D-2%2Cx-y%3D3%2C%E6%B1%82%28x%2By%29%28x-y%29-y%26sup2%3B%2B%28x-y%29%26sup2%3B-%286x%26sup2%3By-2xy%26sup2%3B%29%C3%B7%282y%29%E7%9A%84%E5%80%BC.)
已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)的值.
已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)的值.
已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)的值.
(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)
=x²-y²-y²+x²-2xy+y²-3x²+xy
=-x²-y²-xy
=-x²-y²+2xy-3xy
=-(x-y)²-3xy
=-3²+6
=-3
(x+y)(x-y)-y2+(x-y)2-(6x2y-2xy2)÷(2y)
=x^2-y^2-y^2+x^2-2xy+y^2-3x^2+xy
=-2x^2-y^2-xy
(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)
=x²-y²-y²+x²-2xy+y²-(6x²y÷2y-2xy²÷2y)
=x²-y²-y²+x²-2xy+y²-(3x²-xy)
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(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy²)÷(2y)
=x²-y²-y²+x²-2xy+y²-(6x²y÷2y-2xy²÷2y)
=x²-y²-y²+x²-2xy+y²-(3x²-xy)
=-x²-y²-xy
=-x²-y²+2xy-3xy
=-(x²+y²-2xy)-3xy
=-(x-y)²-3xy
=-3²+6
=-3
收起
第二个等式变为y=x-3代人一式得,x²-3x+2=0。原式=3(x+y)-y²+9-(3x²-xy)=3(x+y)-y²+7-3x²=3(2x-3)-(x-3)²+7-3x²=-4(x²-3x+2)-3=-3