Упр.508 Рабочая тетрадь №3 ГДЗ Мерзляк Полонский 6 класс (Математика)
- Найдите значение выражения:
1) $$7{,}2 : (8 — 10) — 4{,}9 : (-1{,}4 + 0{,}7);$$
2) $$\left(1\frac{16}{21} — 3\frac{4}{9}\right) : \left(-1\frac{11}{42}\right) + 1\frac{5}{7} : (-4).$$
1) $$7,2 : (8 — 10) — 4,9 : (-1,4 + 0,7)$$
$$8 — 10 = -2$$
$$-1,4 + 0,7 = -0,7$$
$$7,2 : (-2) = -3,6$$
$$4,9 : (-0,7) = -7$$
$$-3,6 — (-7) = -3,6 + 7 = 3,4$$
2) $$\left(1 \frac{16}{21} — 3 \frac{4}{9}\right) : \left(-1 \frac{11}{42}\right) + 1 \frac{5}{7} : (-4)$$
$$1 \frac{16}{21} = \frac{37}{21}, \quad 3 \frac{4}{9} = \frac{31}{9}$$
$$\frac{37}{21} — \frac{31}{9} = \frac{111}{63} — \frac{217}{63} = -\frac{106}{63} = -1 \frac{43}{63}$$
$$-1 \frac{11}{42} = -\frac{53}{42}$$
$$-\frac{106}{63} : \left(-\frac{53}{42}\right) = -\frac{106}{63} \cdot \left(-\frac{42}{53}\right) = \frac{4}{3} = 1 \frac{1}{3}$$
$$1 \frac{5}{7} = \frac{12}{7}$$
$$\frac{12}{7} : (-4) = \frac{12}{7} \cdot \left(-\frac{1}{4}\right) = -\frac{3}{7}$$
$$1 \frac{1}{3} — \frac{3}{7} = \frac{28}{21} — \frac{9}{21} = \frac{19}{21}$$
Ответ: 1) $$3,4$$; 2) $$\frac{19}{21}$$.
