Question

suma gaos 2+4+6+...2004=

Answer 1

2004*(2004+1)supra2 =2004*2005supra 2(se simplifica 2 si 2004) =1002*2005=2009010 

Answer 2

$\displaystyle 2+4+6+...+2004=2(1+2+3+...+1002)= \\ \\ =2 \cdot \frac{1002(1002+1)}{2} =2 \cdot \frac{1002 \cdot 1003}{2} =\not 2 \cdot \frac{1005006}{\not 2} =1005006$