👤

a = 2017 + 2
(1+2+3+4
+3+ 2016)


Răspuns :

a = 2017 + 2(1 + 2 + 3 + ... + 2016)

Folosesti formula lui Gauss:

a = 2017 + 2 × 2016 × 2017 : 2

a = 2017 + 2016 × 2017

Acum dai factor comun:

a = 2017 × (1 + 2016)

a = 2017 × 2017

a = 2017²