Question

2+4+6......+26+28+30 =? Rezolvare va rog

Answer 1

S=2+4+6+..+30
S=2( 1+2+3+..+15)  Aplicăm suma lui Gauss
S=2 ×$\frac{15*16}{2}$
S=2×$\frac{240}{2}$
S= 2 ×120
S=240 
Baftă!

Answer 2

2+4+6......+26+28+30= 2*(1+2+3+...+14+15)= 2*15*16/2= 240