Răspuns :
Răspuns:
Explicație pas cu pas:
2 × ( 1 + 2 + 3 + ..... + 2019 ) + 2020 =
= 2 × 2019 × ( 1 + 2019) : 2 + 2020 =
= 2019 × 2020 + 2020 =
= 2020 × ( 2019 + 1 ) =
= 2020 × 2020 =
= 2020² → patrat perfect
Răspuns:
2(1+2+3 + ... +2019)+2020=
2(2019·2020:2)+2020=
2029·2020+2020=
2020(2029+1)=
2020·2020=2020² este patrat perfect