Question

2005+2+4+6+8+.…+4008

Va rog, e urgent

Answer 1

[tex]S=2+4+6+8+...+4008+2005\\ S=2(1+2+3+4+...+2004)+2005\\ [/tex]

Ne folosim de formula sumei lui Gauss, $\frac{n(n+1)}{2}$
[tex]S = 2(\frac{(2004 * 2005)}{2}) + 2005\\ S = 2004 * 2005 + 2005 \\ S = 2005 ^{2}\\ S = 4020025[/tex]