令√x=m,√(y-1)=n,√(z-2)=p(m,n,p均为非负实数),则
x=m^2 y=n^2+1 z=p^2+2
原等式变为
m+n+p=(m^2+n^2+1+p^2+2)/2
整理,得
m^2-2m+1+n^2-2n+1+p^2-2p+1=0
(m-1)^2+(n-1)^2+(p-1)^2=0
平方项恒非负,现在和=0,则各项均=0
m-1=0 m=1 x=m^2=1
n-1=0 n=1 y=n^2+1=2
p-1=0 p=1 z=p^2+2=3
xyz=1×2×3=6