👤

1+2+3+....+2019
19+20+....+75
2+4+6+......+40
5+10+15+......+75
15+18+21+......+90
36+42+48+....+150
Dau coronă


Răspuns :

Răspuns:

2019×2020:2=2019×1010=2.039.190

5×1+5×2+...+5×15=5×(15×16:2)

=5×120

=600 (asta e a patra)

2×1+2×2+...+2×20=2×(20×21:2)

=2×210=420