Question

Alfati ultima cifra al lui p = 3^{2015} - 3^{2014} - 3^{2013}

"^" reprezinta "la puterea"

Answer 1

$p=3^{2015}-3^{2014}-3^{2013}$
$=3^{2013}(3^2-3-1)$
$=3^{2013}(9-3-1)$
$=3^{2013}\cdot5$
$3^{2013}~este~impar,~deci~u(5\cdot3^{2013})=5$

Answer 2

p = 3^2015 - 3^2014 - 3^2013
2015 = 503×4+3
2014 = 503×4+2
2013 = 503×4+1

U(3^2015) = U(3^3) = U(27 )
U(3^2014 )= U(3^2) = U(9)
U(3^2013) = U(3^1) = U( 3 )

p =U (27 -9 -3) =U(15) = 5 (ultima cifra)