Question

Answer 1

a: \(5^{61}+25^{31}+125^{21}\)

\(=5^{61}+5^{62}+5^{63}\)

\(=5^{61}\left(1+5+5^2\right)\)

\(=5^{61}\cdot31⋮31\)

b: \(5^5-5^4+5^3\)

\(=5^3\left(5^2-5+1\right)\)

\(=5^3\cdot21⋮7\)

Answer 2

Đề bài câu b sai rồi nhé.

a) \(5^{61}+25^{31}+125^{21}=5^{61}+5^{62}+5^{63}=5^{61}\left(1+5+5^2\right)=5^{61}.31⋮31\)