2
C
  2021

is gelijk
aan 		A.  1+ 2 + 3 +...+ 2019
B.  1+ 2 + 3 +...+ 2020
C.  1+ 2 + 3 +...+ 2021
D.  1+ 2 + 3 +...+ 2022
E.  1+ 2 + 3 +...+ 2023
A    B    C    D    E

[ 6-6879 - op net sinds 13.7.2020-(E)-13.7.2024 ]

Translation in   E N G L I S H

IN CONSTRUCTION

Oplossing - Solution

C20212 = ½.2021.2020
1 + 2 + 3 + ... + 2020 = ½2020.(1 + 2020) = ½.2020.2021
gricha