fie sirul 2,7;12,17,...202 aflati suma numerelor

Răspuns :

2 + 7 + 12 + 17 + ...+ 202 =

aflam cati termeni are sirul
(202 - 2) : 5 + 1 = 200:5 + 1 = 41

= (2 + 202) × 41 : 2 =

= 204 × 41 : 2 =

= 102 × 41 =

= 4 182