原题:
非零实数$a,bc,$满足$abc=2$,求证:三个实数$2a-\frac{1}{b},2b-\frac{1}{c},2c-\frac{1}{a}$中至多有2个大于2.
引申题1:
实数$a,b,c,d$满足$abcd=2$,问:$2a-\frac{1}{b},2b-\frac{1}{c},2c-\frac{1}{d},2d-\frac{1}{a}$中至多有几个大于2?
引申题2:
若$a_i\inR,n\inN^*,\prod_{i=1}^na_i=2$,问:$2a_i-\frac{1}{a_{i+1}}(i=1,2,\cdots ,n,a_{n+1}=a_1)$中至多有几个大于2?
求解答(特别是引申题2) |