Question

Cate numere naturale de forma 35a bara sunt divizibile cu 3?

Answer 1

[tex]Pentru~ca~35a|3=\ \textgreater \ (3+5+a)|3\\ =\ \textgreater \ 8+4=12|3\\ =\ \textgreater \ 8+7=15|3\\ 35a|3=\ \textgreater \ a=4,7\\ =\ \textgreater \ 35a|3|3+5+(4+7)=(12,15)|3[/tex]

Answer 2

3|35a=>3|(3+5+a)=>a€{1,4,7};Nr sunt 351,354,357(3 numere )