Question

Calculatii:
a)1+2+3+...+2006
b)2+4+6+...+2006
c)1+3+5+...+2005
Datimi definiti la ficare+ explicatie
Va rogggg!!!

Answer 1

e o formula :
pt a afla cati termeni sunt
iei (ultimul term-primul term) : ratie +1
ratie = diferenta dintre termenii sumei

pt a calcula suma
iei (ultimul term + primul term) * nr termeni :2

1+2+3+...+2006
nr term
(2006-1):1+1=2005:1+1=2005+1=2006
suma
(2006+1)*2006:2=2007*1003=2013021

2+4+6+...+2006
nr term
(2006-2):2+1=2004:2+1=1002+1=1003
suma
(2006+2)*1003:2=2008*1003:2=2014024:2= 1007012

la fel si la ultima... vezi daca ai inteles. succes