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问题: 高中不等式

设x,y,z是互不相等的实数,且x+y+z>0.求证:
x^3/[(x-y)(x-z)]+y^3/[(y-z)(y-x)]+z^3/[(z-x)(z-y)]>0

解答:

设x,y,z是互不相等的实数,且x+y+z>0.求证:
x^3/[(x-y)(x-z)]+y^3/[(y-z)(y-x)]+z^3/[(z-x)(z-y)]>0

x^3/[(x-y)(x-z)]+y^3/[(y-z)(y-x)]+z^3/[(z-x)(z-y)]
=[x^3*(y-z)+y^3*(z-x)+z^3*(x-y)]/[(x-y)(y-z)(x-z)]
=x+y+z>0