[tex]1 = 5^0 \\
5^0+5^1+5^2+5^3+5^4+5^5+...+5^{2012}+ 5^{2013}= \\ ~~~(Grupam ~cate ~2~ termeni. ~~~\text{Putm grupa deoarece avem 2014 termeni})\\
=(5^0+5^1)+(5^2+5^3)+(5^4)+(5^5)+...+(5^{2012}+ 5^{2013})= \\
=1(5^0+5^1)+5^2(5^0+5^1)+5^4(5^0+5^1)+...+5^{2012}(5^0+5^1)= \\
=(5^0+5^1)(1+5^2+5^4+...5^{2012})= \\ =(1+5)(1+5^2+5^4+...5^{2012})= \\
=6(1+5^2+5^4+...5^{2012}) ~\vdots ~ 6 \\
cctd[/tex]