已知m2(m的平方)=n+2,n2(n的平方)=m+2(m不等于n),求m3(m的立方)-2mn+n3(n的立方)
人气:124 ℃ 时间:2020-05-13 14:18:23
解答
m^2=n+2 一式
n^2=m+2 二式
一式减二式:
m^2-n^2=n-m
(m+n)*(m-n)=n-m
(1)若m=n
则m^3-2mn+n^3=2m^2*(m-1)
(2)若m不等于n
则:m+n=-1
则m^3-2mn+n^3=m*(n+2))-2mn+n*(m+2)=2(m+n)=-2
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