Упр.755 Часть 3 ГДЗ Дорофеев Петерсон 6 класс (Математика)

а)

$$-5\frac{1}{4}\cdot \frac{3}{7}:(-1{,}8)\cdot \left(-\frac{2}{5}\right)^2 = -\frac{21}{4}\cdot \frac{3}{7}:\left(-\frac{9}{5}\right)\cdot \frac{4}{25}$$
$$= -\frac{63}{28}:\left(-\frac{9}{5}\right)\cdot \frac{4}{25} = -\frac{9}{4}\cdot \left(-\frac{5}{9}\right)\cdot \frac{4}{25} = \frac{1}{5}=0{,}2$$

б)

$$\frac{-0{,}7\cdot 0{,}06\cdot (-1{,}2)}{0{,}024\cdot \left(-\frac{1}{6}\right)\cdot 5{,}6} = \frac{\frac{7}{10}\cdot \frac{6}{100}\cdot \frac{12}{10}}{\frac{24}{1000}\cdot \left(-\frac{1}{6}\right)\cdot \frac{56}{10}}$$
$$= \frac{7\cdot 6\cdot 12}{24\cdot (-1)\cdot 56} = \frac{7\cdot 3}{-1\cdot 8} = -\frac{21}{8} = -2{,}625$$

в)

$$\left(-\frac{9}{14}:(-5\frac{1}{7})+9{,}31:(-24{,}5)\right):(-0{,}5)^2-0{,}08$$
$$= \left(-\frac{9}{14}:\left(-\frac{36}{7}\right)+\frac{931}{100}:\left(-\frac{49}{2}\right)\right):\frac{1}{4}-0{,}08$$
$$= \left(\frac{9}{14}\cdot \frac{7}{36}-\frac{931}{100}\cdot \frac{2}{49}\right):\frac{1}{4}-0{,}08 = \left(\frac{1}{8}-0{,}38\right)\cdot 4-0{,}08$$
$$= (-0{,}255)\cdot 4-0{,}08 = -1{,}02-0{,}08 = -1{,}1$$

г)

$$\frac{\left(-2{,}75\cdot 2\frac{2}{11}-1\frac{7}{8}\cdot (-3{,}2)\right):\left(2\frac{9}{40}-0{,}275\right)}{2{,}47:0{,}26-\left(-5\frac{3}{11}:5\frac{3}{11}\right)^2}$$
$$= \frac{\left(-\frac{11}{4}\cdot \frac{24}{11}+\frac{15}{8}\cdot \frac{32}{10}\right):\left(2\frac{9}{40}-0{,}275\right)}{9{,}5-(-1)^2}$$
$$= \frac{(-6+6):1{,}95}{9{,}5-1} = \frac{0}{8{,}5} = 0$$

Ответ

а) $$0{,}2$$; б) $$-2{,}625$$; в) $$-1{,}1$$; г) $$0$$.