Question

buna va rog si eu sa imi rezolvați aceste sume:
1. 1+2+3+......+150
2. 2+4+6+......+188
3. 65+66+67+....+111

Answer 1

Răspuns:

1. 1+2+3+......+150=[(150·(150+1)]/2=150·151:2=11325

2. 2+4+6+......+188 = 2(1+2+3+...+94)=2·94·95:2=8930

3. 65+66+67+....+111=

111-65+1=47 termeni

47(65+111):2=47·176:2=4136

suma lui Gauss

1 + 2 + 3 + 4 + … + n = n·( n + 1 ) : 2