Задание 249 Вариант 1 Самостоятельная работа ГДЗ Дидактические материалы Чесноков 6 класс (Математика)

а) $$-2{,}8\cdot(-35):(-0{,}49)-\frac{5}{13{,}25}:(-5{,}3)\cdot(-0{,}8)$$

$$-2{,}8\cdot(-35)=98$$
$$98:(-0{,}49)=-200$$
$$-13{,}25:(-5{,}3)=2{,}5$$
$$2{,}5\cdot(-0{,}8)=-2$$
$$-200-(-2)=-200+2=-198$$

б) $$-3\frac{1}{3}\cdot\left(-2\frac{3}{4}:1\frac{5}{2}\right)$$

$$-2\frac{3}{4}:5\frac{1}{2}=-\frac{11}{4}:\frac{11}{2}=-\frac{11}{4}\cdot\frac{2}{11}=-\frac{1}{2}$$
$$-3\frac{1}{3}\cdot\left(-\frac{1}{2}\right)=\frac{10}{3}\cdot\frac{1}{2}=\frac{10}{6}=\frac{5}{3}=1\frac{2}{3}$$

в) $$2\frac{2}{5}: \left(1\frac{11}{15}-3\frac{2}{5}\right)$$

$$1\frac{11}{15}-3\frac{2}{5}=1\frac{11}{15}-3\frac{6}{15}= \frac{26}{15}-\frac{51}{15}=-\frac{25}{15}=-\frac{5}{3}$$
$$2\frac{2}{5}:\left(-\frac{5}{3}\right)=\frac{12}{5}:\left(-\frac{5}{3}\right)=\frac{12}{5}\cdot\frac{3}{5}=-\frac{36}{25}=-1\frac{11}{25}$$

Ответ: а) $$-198$$; б) $$1\frac{2}{3}$$; в) $$-1\frac{11}{25}$$.