x-y=4,xy=-2,求代数式〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕的值现在立刻马上就要
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![x-y=4,xy=-2,求代数式〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕的值现在立刻马上就要](/uploads/image/z/341877-21-7.jpg?t=x-y%3D4%2Cxy%3D-2%2C%E6%B1%82%E4%BB%A3%E6%95%B0%E5%BC%8F%E3%80%942x%2B3y-2xy%E3%80%95-%E3%80%94x%2B4y%2Bxy%E3%80%95-%E3%80%943xy%2B2y-2x%E3%80%95%E7%9A%84%E5%80%BC%E7%8E%B0%E5%9C%A8%E7%AB%8B%E5%88%BB%E9%A9%AC%E4%B8%8A%E5%B0%B1%E8%A6%81)
x-y=4,xy=-2,求代数式〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕的值现在立刻马上就要
x-y=4,xy=-2,求代数式〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕的值
现在立刻马上就要
x-y=4,xy=-2,求代数式〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕的值现在立刻马上就要
〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕
=2x+3y-2xy-x-4y-xy-3xy-2y+2x
=(2x-x+2x)+(3y-4y-2y)-(2xy+xy+3xy)
=3x-3y-6xy
=3(x-y)-6xy
=3*4-6*(-2)
=12-(-12)
=24
〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕=3x-3y-6xy=3(x-y)-6xy=3*4-6*(-2)=12+12=24
〔2x+3y-2xy〕-〔x+4y+xy〕-〔3xy+2y-2x〕
=2x+3y-2xy-x-4y-xy-3xy-2y+2x
=(2x-x+2x)+(3y-4y-2y)-(2xy+xy+3xy)
=3x-3y-6xy.
原式=2x+3y-2xy-x-4y-xy-3xy-2y+2x
=(2x-x+2x)+(3y-4y-2y)-(2xy+xy+3xy)
=3x-3y-6xy
=3(x-y+2xy)
把x-y=4 xy=-2代入
原式=24