Question

Scrieti numerele naturale de doua cifre care au cifra zecilor de doua ori mai mare ca cifra unitatilor . 

Answer 1

21 42 63  84 --------------------------------------------------------------------------

Answer 2

$Nr \ sunt \ de \ forma \ xy \\\\ x=2y \\\\ x;y \ \in \ N \\\\\\ y=1 \ => x=2 \to\boxed{21} \\\\ y=2 \ =>x=4 \to\boxed{42} \\\\ y=3 \ =>x=6 \to \boxed{63} \\\\ y=4 \ => x=8 \to \boxed{84} \\\\ \boxed{\boxed{xy=\{21;42;63;84 \}}}$