Предмет: Математика, автор: talata

собрались 12 волейболистов и 9 теннисистов , а всего -16 человек.сколько из них играют и в волейбол, и в теннис?

Ответы

Автор ответа: Аноним

х -число чистых волейболистов

у - число чистых теннисистов

с - число совмещающих волейбол и теннис

х + с = 12 - волейболисы

у + с = 9 - теннисисты

х + у + с = 16 -все спортсмены /·2

Из 1-го уравнения х = 12-с

Из 2-го уравнения у = 9 - с

подставим в 3-е уравнение

12 - с + 9 - с + с = 16

21 - с = 16

с = 5

Ответ: и в волейбол, и в теннис играют 5человек

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Преобразуйте выражение, используя распределительное свойство умножения;
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