[tex] \frac{x1 + x2 + x3 + ... + x2020}{2020} = 2020 \\ = > x1 + x2 + x3 + ... + x2020 = 2020 \times 2020 \\ x1 + x2 + x3 + ... + x2020 = s1 \\ \\ \frac{x1 + x2 + x3 + ... + x2019}{ 2019} = 2019 \\ = > x1 + x2 + x3 + ... + x2019 = 2019 \times 2019 \\ x1 + x2 + x3 + ... + x2019 = s2 \\ = > x2020 = s1 - s2 = {2020}^{2} - {2019}^{2} [/tex]
Calculele le poți face și tu. :))
