Question

Sa se arate ca a,(b)+b,(a)=(a+b)•1,(1)

Answer 1

[tex]a,(b)=a \frac{b}{9}= \frac{9a+b}{9} [/tex]
$b,(a)= b\frac{a}{9}= \frac{9b+a}{9}$
Suma lor este $\frac{10(a+b)}{9}$
(a+b)·1,(1)=$\frac{9+1}{9} (a+b)$
Dar $\frac{10(a+b)}{9}$=$\frac{9+1}{9} (a+b)$. 
Astfel egalitatea este demonstrata