Question

2+4+6+...+100=
5+10+15+...+500=
(Va rog rezolvari complete)

Answer 1

2+4+6+...+100=
2(1+2+3+..+50)=
1+2+3+...+50= facem gauss
50*51/2

2*50*51/2  simplificam 2 cu 2 si ramane
50*51=2550

5+10+..+500=
5(1+2+3+...+100)=
Gauss din nou in paranteza
100*101/2=
50*101=
5*50*101=25250