Question

Determinati nr nat de forma ab stiind ca ab+ba=2•a+2•b+27

Answer 1

ab si ba in baza 10, nu?
10a+b+10b+a=2a+2b+27
11a+11b=2a+2b+27
11(a+b)=2(a+b)+27
9(a+b)=27
a+b=3
ab(in baza 10)=30,12,21;