1≤a≤b≤c,证明log(a)(b)+log(b)(c)+log(c)(a)≤log(b)(a)+log(c)(b)+log(a)(c)
问题描述：
1≤a≤b≤c,证明log(a)(b)+log(b)(c)+log(c)(a)≤log(b)(a)+log(c)(b)+log(a)(c)
答
log(a)(b)=x>=1,log(b)(c)=y>=1,则log(c)(a)=1/xy,log(b)(a)=1/x,log(c)(b)=1/y,log(a)(c)=xy
然后作差比较