[tex]a+b\ \textgreater \ 2 \sqrt{ab} \\
(a+b)^{2} \ \textgreater \ 2ab \\
a^{2} + b^{2} + 2ab \ \textgreater \ 4ab \\
a^{2} + b^{2} +2ab -4ab \ \textgreater \ 0 \\
a^{2} + b^{2} -2ab \ \textgreater \ 0 \\
(a-b)^{2} \ \textgreater \ 0 [/tex]
adevarat deoarece orice patrat este mai mare sau egal cu 0
