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Galati 2008

Posted: Sat Nov 29, 2008 2:32 pm
by alex2008
Sa se arate ca oricare ar fi numerele reale \( a,b,c \in(0;1) \) , avem inegalitatea :
\( \sqrt{\frac{ab}{ab+c\cdot(a+b+c)}}+\sqrt{\frac{bc}{bc+a\cdot(a+b+c)}}+\sqrt{\frac{ca}{ca+b\cdot(a+b+c)}}\le \frac{3}{2} \)

Posted: Sat Nov 29, 2008 3:13 pm
by Marius Mainea
Folosind inegalitatea mediilor avem :
\( \sum\sqrt{\frac{ab}{ab+c(a+b+c)}}=\sum{sqrt{\frac{ab}{(c+a)(c+b)}}}\le \sum{\frac{1}{2}(\frac{a}{c+a}+\frac{b}{c+b})}=\frac{1}{2}(1+1+1)=\frac{3}{2} \)