Question

efectuati 2+4+6....+50

Answer 1

2+4+6+8+...+50=2(1+2+3+4+...+25)

$1+2+3+...+25= \frac{25.26}{2}$
(punctul e ori)

deci 2+4+6+8+...+50=2·25·26/2=25·26=650

Answer 2

2 + 4 + 6 ..... + 50 =  
Asa Dau in factor comun pe 2

2 ( 1 + 2+ 3 ... + 25 ) = 
 
In paranteza e suma lu Gauss

2(25 x 26 /2) = 
2( 25 x 13 ) =     325 x 2 = 650 .