Упр.184 Вариант 2 Дидактические материалы ГДЗ Мерзляк Полонский 6 класс (Математика)

Выполните действия:

1. 1) $$-12{,}6\cdot0{,}7+4{,}8\cdot(-1{,}7)$$; 2) $$(-5{,}16+5{,}09)\cdot(3{,}5-4)$$; 3) $$\frac{4}{7}\cdot\left(-5\frac{5}{6}\right)-\frac{5}{62}\cdot\left(-4\frac{3}{7}\right)$$; 4) $$\left(5\frac{1}{4}-6\frac{1}{6}\right)\cdot\left(3\frac{1}{4}-0{,}55\right)$$.

1) $$-12{,}6 \cdot 0{,}7 + 4{,}8 \cdot (-1{,}7) = -8{,}82 — 8{,}16 = -16{,}98.$$

2) $$(-5{,}16 + 5{,}09)\cdot(3{,}5 — 4) = (-0{,}07)\cdot(-0{,}5) = 0{,}035.$$

3) $$\frac{4}{7}\cdot\left(-5\frac{5}{6}\right)-\frac{5}{62}\cdot\left(-4\frac{3}{7}\right)$$

$$=\frac{4}{7}\cdot\left(-\frac{35}{6}\right)-\frac{5}{62}\cdot\left(-\frac{31}{7}\right)$$

$$=-\frac{4\cdot 35}{7\cdot 6}+\frac{5\cdot 31}{62\cdot 7}=-\frac{10}{3}+\frac{5}{14}$$

$$=-\frac{140}{42}+\frac{15}{42}=-\frac{125}{42}=-2\frac{41}{42}.$$

4) $$\left(5\frac{1}{4}-6\frac{1}{6}\right)\cdot\left(3\frac{1}{4}-0{,}55\right)$$

$$=\left(5\frac{3}{12}-6\frac{2}{12}\right)\cdot\left(3\frac{1}{4}-\frac{55}{100}\right)$$

$$=\left(5\frac{3}{12}-5\frac{14}{12}\right)\cdot\left(3\frac{1}{4}-\frac{11}{20}\right)$$

$$=-\frac{11}{12}\cdot\left(3\frac{5}{20}-\frac{11}{20}\right)=-\frac{11}{12}\cdot 2\frac{14}{20}$$

$$=-\frac{11}{12}\cdot 2\frac{7}{10}=-\frac{11}{12}\cdot\frac{27}{10}=-\frac{99}{40}=-2\frac{19}{40}.$$

Ответ: 1) $$-16{,}98$$; 2) $$0{,}035$$; 3) $$-2\frac{41}{42}$$; 4) $$-2\frac{19}{40}$$.