Question

2+4+6+.......+50
Va roog!

Answer 1

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


( punctul este ori ) ( bara este supra ) 

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

Answer 2

$2+4+6+...+50 = \\ \\ = 2\cdot (1+2+3+...+25) = \\ \\ = 2\cdot \dfrac{25\cdot(25+1)}{2} = \\ \\ = 25\cdot 26 = \\ \\ = 650$