Предмет: Математика, автор: NatashaLov

У саши 14 фломастеров, а у кати-9, сколькими способами саша может обменять 2 своих фломастера на 2 фломастера кати, если все фломастеры различны?

Ответы

Автор ответа: Polinaa98

каждый фломастер кати можно объменять ещё с восмью. вывод надо 8*9=72

даказательство расписуем все фломастеры под числа: 1,2,3.4.5.6.7.8.9 объмениваем сначала 1и2 затем 1и3 потом 1и4,1и5,1и6, 1и7,1и8,1и9 вот уже 9 способов далее так можно объменять 2и1,2и3,2и4,2и5,2и6,2и7,2и8,2и9 если далее так расписовать в итоге бедет 72

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