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inequality for logarit

Source: Croatian NMC 2005, 2nd Grade

May 8, 2007
inequalitieslogarithmsinequalities proposed

Problem Statement

If a,b,ca, b, c are real numbers greater than 11, prove that for any real number rr (logabc)r+(logbca)r+(logcab)r32r.(\log_{a}bc)^{r}+(\log_{b}ca)^{r}+(\log_{c}ab)^{r}\geq 3 \cdot 2^{r}.