Раскройте скобки и сосчитайте (х-умножить) зарание ) а) 0.5 х (2а-4б)= б) -2 х (1.5с - 6) + 7-3с= в)2 х (4-а) + 8 х (в-1)=

a) 0,5 * (2a - 4b) = 0,5 * 2a - 0,5 * 4b = a - 2b

б) - 2 * (1,5c - 6) + 7 - 3c = - 2 * 1,5c - 2 * (- 6) + 7 - 3c = - 3c + 12 + 7 - 3c =

= 19 - 6c

в) 2 * (4 - a) + 8 * (b - 1) = 8 - 2a + 8b - 8 = 8b - 2a

а) 0.5 x (2a-4b)=a-2b

б) -2 x (1,5c-6)+7-3с=-3c+12+7-3с=19-6с

в) 2 x (4-a) + 8 x (b-1)=8-2a+8b-8=8b-2a

Объяснение:

Пусть х - количество рядов в синем зале, тогда (х + 2) - количество рядов в пурпурном зале, но в каждом ряду на 4 места меньше. Уравнение:

648/х - 640/(х+2) = 4

648 · (х + 2) - 640 · х = 4 · х · (х + 2)

648х + 1296 - 640х = 4х² + 8х

8х + 1296 = 4х² + 8х

1296 = 4х² + 8х - 8х

4х² = 1296

х² = 1296 : 4

х² = 324

х = √324

х = 18 - количество рядов в синем зале

18 + 2 = 20 - количество рядов в пурпурном зале

ответ: 18 рядов и 20 рядов.

Проверка:

640 : 20 = 32 - количество мест в одном ряду в пурпурном зале

648 : 18 = 36 - количество мест в одном ряду в синем зале

36 - 32 = 4 - на столько меньше мест в одном ряду пурпурного зала

ЖЕДАЛЙАШОВАПРЫГНРМ ВППЦКП

Объяснение:

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