Предмет: Алгебра, автор: gangstar2302233255

7 класс Олимпмада 4.Сосчитай: 1+2-3-4+5+6-7-8+9+10-...+2002-2003-2004+2005

Ответы

Автор ответа: карина2333

Объединим в группы по четыре члена, начиная со второго
2 - 3 - 4 + 5 = 0
6 - 7 - 8 + 9 = 0
10 - 11 - 12 + 13 = 0
и т. д... .
2002 - 2003 - 2004 + 2005 = 0
Всё по нулям, но остается первое слагаемое

Автор ответа: LASST

Ответ: 1+2-3-4+5+6-7-8+9+10-(11)+2002-2003-2004+2005
Ответ: 11

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