Question

vă rooooooooooggg frumooooossss!!!!​

Answer 1

Răspuns:

$a) \:2019^{2} - 2019 * 2020 = 2019 * (2019 -2020) = 2019 * (-1) = \boxed{-2019}\\\\\\b)\:2019^{2} - 2018 * 2019 = 2019 *(2019 - 2018)= 2019 * 1 = \boxed{2019}\\\\\\c) \: 5+10+15+........+2020 - 5*(1+2+3+.......+404) = \\\\5*(1+2+3+.......+404) - 5*(1+2+3+.......+404) = \boxed{0}$

Answer 2

Răspuns:

Explicație pas cu pas:

a)

2019^2 - 2019*2020 = 2019*(2019 - 2020) = -2019

b)

2019^2 - 2018*2019 = 2019*(2019 - 2018) = 2019

c)

5 + 10 + 15 + ...+ 2020 - 5*(1 + 2 + 3 + ...+ 404)

= 5*(1 + 2 + 3 + ...+ 404) - 5*(1 + 2 + 3 + ...+ 404) = 0