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
