Question

Calculeaza:1+4+7+...+301=?

Answer 1

1 + 4 + 7 + ....... + 301 = 15 251

→ stabilesc cati termeni are suma cu ratia 3 ( 4 - 1 = 3;   7 - 4 = 3;...... )

( 301 - 1 ) : 3 + 1 = 300 : 3 + 1 = 101 termeni are suma

→ aplic formula sumei lui Gauss

= 101 × ( 1 + 301 ) / 2 =

= 101 × 302 / 2 =

= 101 × 151 =

= 15 251