(xy-1)的平方-(x+y-2xy)(2-x-y)

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(xy-1)的平方-(x+y-2xy)(2-x-y)

(xy-1)的平方-(x+y-2xy)(2-x-y)
(xy-1)的平方-(x+y-2xy)(2-x-y)

(xy-1)的平方-(x+y-2xy)(2-x-y)
(xy-1)²-(x+y-2xy)(2-x-y)
=(xy-1)²+(x+y-2xy)(x+y-2)
=x²y²-2xy+1+(x+y)²-2(x+y)-2xy(x+y)+4xy
=x²y²-2x²y-2xy²+x²+y²+4xy-2x-2y+1

原式=x^y^-2xy+1-2x+x^+xy-2y+xy+y^+4xy-2x^y-2xy^=x^y^-2x^y+x^-2xy^+4xy-2xy^+y^-2y+1输入太费事了。整糊涂了。展开就可以了。^是平方的意思。

=(xy-1)²+(x+y-2xy)(x+y-2)
=x²y²-2xy+1+(x+y)²-2(x+y)-2xy(x+y)+4xy
=x²y²-2x²y-2xy²+x²+y²+4xy-2x-2y+1

(xy-1)²-(x+y-2xy)(2-x-y)
=(xy-1)²+(x+y-2xy)(x+y-2)
=x²y²-2xy+1+(x+y)²-2(x+y)-2xy(x+y)+4xy
=x²y²-2x²y-2xy²+x²+y²+4xy-2x-2y+1
(xy-1...

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(xy-1)²-(x+y-2xy)(2-x-y)
=(xy-1)²+(x+y-2xy)(x+y-2)
=x²y²-2xy+1+(x+y)²-2(x+y)-2xy(x+y)+4xy
=x²y²-2x²y-2xy²+x²+y²+4xy-2x-2y+1
(xy-1)²+(x+y-2)(x+y-2xy)
=x²y²-2xy+1+(x+y)²-2xy(x+y)-2(x+y)+4xy
=x²y²+2xy+1+(x+y)²-2xy(x+y)-2(x+y)
=(xy+1)²-2(xy+1)(x+y)+(x+y)²
=(xy+1-x-y)²
=[x(y-1)-(y-1)]²
=(x-1)²(y-1)²

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