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

1) -12,6 · 0,7 + 4,8 · (-1,7);
2) (-5,16 + 5,09) · (3,5 — 4);
3) 4/7 · (-5 5/6) — 5/62 · (-4 3/7);
4) (5 1/4 — 6 1/6) · (3 1/4 — 0,55).

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

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

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

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

$$=-\frac{11}{12}\cdot\left(2\frac{25}{20}-\frac{11}{20}\right)=-\frac{11}{12}\cdot 2\frac{7}{10}$$

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

Ответ

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