已知a已知a
已知aa=2√(b/c)(c/b)]=2,(a+b+c)(1/a+1/b+1/c )=a/a+a/b+a/c+b/a+b/b+b/c+c/a+c/b+c/c=3+a/b+b/a+a/c+c/a+b/c+c/b>=3+2+2+2=9,-(1/a+1/b+1/c )>=9,1/a+1/b+1/c