Question

$6 + 11 + 16 + 21 + ..... + 506$
Va rog mult
Repede

Answer 1

6 + 11 + 16 + 21 + ... + 506 = 25 856

→ stabilesc cati termeni are suma cu ratia = 5 ( 11 - 6= 5;    16 - 11 = 5;..... )

( 506 - 6 ) : 5 + 1 = 500 : 5 + 1 = 101 termeni are suma

→ aplic formula sumei lui Gauss

= 101 × ( 6 + 506 ) : 2 =

= 101 × 512 : 2 =

= 101 × 256 =

= 25 856