Question

(2^n*5^n+1+2^n+1*5^n*11) este multiplu de 9 N€IN

Answer 1

$2^n\cdot5^{n+1}+2^{n+1}\cdot5^n\cdot11 \\ \\ 2^n\cdot5^n\cdot5+2^n\cdot2\cdot5^n\cdot11 \\ \\ 10^n\cdot5+10^n\cdot22 \\ \\ =10^n\cdot27 \\ \\ =10^n\cdot3\cdot9~\vdots~9$