1.已知x/y=1/2,则x^2-3xy+2y^2的值为?2.m^3-m-2=0,则(m^3/m+2)-[(m^3-m)/2]=?

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1.已知x/y=1/2,则x^2-3xy+2y^2的值为?2.m^3-m-2=0,则(m^3/m+2)-[(m^3-m)/2]=?
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1.已知x/y=1/2,则x^2-3xy+2y^2的值为?2.m^3-m-2=0,则(m^3/m+2)-[(m^3-m)/2]=?
1.已知x/y=1/2,则x^2-3xy+2y^2的值为?
2.m^3-m-2=0,则(m^3/m+2)-[(m^3-m)/2]=?

1.已知x/y=1/2,则x^2-3xy+2y^2的值为?2.m^3-m-2=0,则(m^3/m+2)-[(m^3-m)/2]=?
x/y=1/2,y=2x
x^2-3xy+2y^2=(y-x)(2y-x)=3x^2
m^3-m-2=0,m^3=m+2,m^3-m=2
(m^3/m+2)-[(m^3-m)/2]=1-1=0

x^2-3xy+2y^2 = x^2 - 6x^2 + 8x^2 = 3x^2
m^3 = m+2
==> (m^3/m+2)-[(m^3-m)/2] = [(m+2)/m+2] - [2/2] = [3+2/m] - 1 = 2 + 2/m