Question

Este suma : S=6+6^2+6^3+...+6^21divizibila cu 43? Demonstrati (calculati)

Answer 1

$S=6(1+6+6^2)+6^4(1+6+6^2)+...+6^{19}(1+6+6^2)=$

$=43\cdot(6+6^4+6^7+...+6^{19})\vdots43$