赞 wannerdance 幼苗
共回答了23个问题采纳率：91.3% 举报
x=m^2-2mn+n^2
x=(m-n)^2
x=(1-2)^2
x=1
y=m^2-2mn-n^2
y=m^2-2mn+n^2-2n^2
y=(m-n)^2-2n^2
y=1-2*2^2
y=-7
x-[y-2x-（x-y）]
=x-[y-2x-x+y]
=x-[2y-3x]
=x-2y+3x
=4x-2y
=4*1-2*(-7)
=4+14
=18
x=(m-n)^2
x=(1-2)^2
x=1
y=m^2-2mn-n^2
y=m^2-2mn+n^2-2n^2
y=(m-n)^2-2n^2
y=1-2*2^2
y=-7
x-[y-2x-（x-y）]
=x-[y-2x-x+y]
=x-[2y-3x]
=x-2y+3x
=4x-2y
=4*1-2*(-7)
=4+14
=18
1年前
7
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