Question

Ex32 Determinati nr naturale scrise in baza zece de borma ab pentru care: ab=4x(a+b)

Answer 1

$\it \overline{aa}=4(a+b) \Rightarrow 10+b=4a+4b \Rightarrow 10-4a=4b-b \Rightarrow 6a=3b \Rightarrow \\ \\ 3b=6a|_{:3} \Rightarrow b=2a \Rightarrow \overline{ab}\in\{12,\ \ 24,\ \ 36,\ \ 48\}$