Răspuns :
2+3+4+...+100-1-2-...-99=
=2-2+3-3+4-4+....+99-99+100-1=
=100-1=
=99
(2-2=0
3-3=0
4-4=0
...............
99-99=0)
=2-2+3-3+4-4+....+99-99+100-1=
=100-1=
=99
(2-2=0
3-3=0
4-4=0
...............
99-99=0)
2+3+4+...+100-1-2-...-99
=-1+2-2+3-3+4-4+..............+99-99+100=100-1=99