Question

Determinati numerele naturale de doua cifre care se micsoreaza cu 45 daca se schimba ordinea lor .

Answer 1

ab-numar natural ,a,b∈N;
⇒ab=ba+45;
⇒10a+b=10b+a+45
⇒45=[10a+b]-[10b+a]
⇒45=9a+[-9b]
⇒45=9a-9b;
⇒45=9[a-b]⇒a-b=5;
⇒a si b-cifre naturale;
⇒a,b∈[[9,4],[8,3],[7,2],[6,1],[5,0];
⇒numerele care respecta cerinta sunt:94,83,72,61,50;