Question

Z=3+5+7+...2015-2-4-6-...-2014

Answer 1

am raspuns acum o ora la o intrebare identica, folositi "search" si economisiti niste puncte :D
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Z=(3+5+7+...+2015)-(2+4+6+...+2014)

3+5+7+...+2015=
Scadem din fiecare termen 1, obtinem
2+4+6+...+2014=2(1+2+3+...+1007) de aici deducem ca avem 1007 termeni din care l-am scazut pe -1
3+5+7+....+2015=(2+4+6+...+2014)+1007

Notam "2+4+6+...+2014" cu x

(x+1007)-x=x+1007-x=1007

Z=1007