Daca media aritmetica a oricare doua numere este cat celalat numar ,pot spune ca numerele sunt egale.
[tex] \frac{a+b}{2} =c =\ \textgreater \ a+b=2c
[/tex]
[tex] \frac{a+c}{2} = b =\ \textgreater \ a+c =2b [/tex]
[tex] \frac{b+c}{2} =a =\ \textgreater \ b+c=2a[/tex]
Le adunam
2a+2b+2c=2a+2b+2c => a=b=c
