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[求助]SOS!!

[求助]SOS!!

已知:实数x,y,z满足
x/(y+z)+y/(x+z)+z/(x+y)=1

求:x2/(y+z)+y2/(x+z)+z2/(x+y)=?

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x+y+z
=(x+y+z)*[x/(y+z)+y/(x+z)+z/(x+y)]
=x+y+z+x2/(y+z)+y2/(x+z)+z2/(x+y)

∴ x2/(y+z)+y2/(x+z)+z2/(x+y)=0

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