首先确定一个不等式即x^2+y^2+z^2≥xy+yz+xz,将x,y,z替换为根号形式则a+b+c≥√ab+√bc+√ac,设a= 3x+2,b=3y+2,c=3z+2,故（√a+√b+√c）^2=a+b+c+2(√ab+√bc+√ac)≤3（a+b+c）,已知a+b+c=9,故（√a+√b+√c）^2≤...
若x,y,z>0,x+y+z=1,求证：（√ 3x+2）+（√3y+2）+（√3z+2）
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