Răspuns :
Calculam ultima cifra a fiecarui termen si obtinem 1
[tex]u \left(9^{4n} - 7^{4n} \right) = 1-1=0 \Longrightarrow 10|9^{4n} - 7^{4n}[/tex]
[tex]u \left(9^{4n} - 7^{4n} \right) = 1-1=0 \Longrightarrow 10|9^{4n} - 7^{4n}[/tex]