Question

2x+7/7,5n+2+5n+1+5n divizibil cu 31,x2y divizibil cu 45, repede va rog ​

Answer 1

$\it a=5^{n+2}+5^{n+1}+5^n=5^n(5^2+5+1)=5^n(25+5+1)=5^n\cdot31\in M_{31}\Rightarrow\\ \\ \Rightarrow a\ \vdots\ 31$