
已知6x-1=2,y平方-y=2,则(5x平方y+5xy-7x)-(4x平方y+5xy-7x=)____
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6x-1=2
x=1/2
y²-y-2=0
(y-2)(y+1)=0
y=2,y=-1
(5x²y+5xy-7x)-(4x²y+5xy-7x)
=5x²y+5xy-7x-4x²y-5xy+7x
=x²y
=(1/2)²×2或(1/2)²×(-1)
=1/2或-1/4
x=1/2
y²-y-2=0
(y-2)(y+1)=0
y=2,y=-1
(5x²y+5xy-7x)-(4x²y+5xy-7x)
=5x²y+5xy-7x-4x²y-5xy+7x
=x²y
=(1/2)²×2或(1/2)²×(-1)
=1/2或-1/4
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