Question

S=2+7+12+17+22+27+……+2012+2017+2022
Va rog mult

Answer 1

Răspuns:

409860

Explicație:

S = 2 + 7 + 12 + 17 + ... + 2012 + 2017 + 2022

S = (5 × 0 + 2) + (5 × 1 + 2) + (5 × 2 + 2) + (5 × 3 + 2) + ... + (5 × 402 + 2) + (5 × 403 + 2) + (5 × 404 + 2)

S = 5 × (1 + 2 + 3 + ... + 404) + 2 × 405 (sunt 405 termeni)

S = (5 × 404 × 405 / 2) + 810

S = 409050 + 810

S = 409860

-Mihai