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Inegalitate cu a, b, c

Posted: Wed Feb 04, 2009 12:49 pm
by alex2008
Daca \( a,b,c \in [\frac{1}{3};3] \) sa se arate ca :

\( \frac{a}{a+b}+\frac{b}{b+c}+\frac{c}{c+a}\ge \frac{7}{5} \)

Posted: Fri Feb 06, 2009 8:24 pm
by Marius Mainea
Daca \( E(a,b,c)=\frac{a}{a+b}+\frac{b}{b+c}+\frac{c}{c+a} \) si \( a=\max\{a,b,c\} \) atunci

\( E(a,b,c)\ge E(a,b,\sqrt{ab})\ge \frac{7}{5} \)