Задание 338 Вариант 3 Самостоятельная работа ГДЗ Дидактические материалы Чесноков 6 класс (Математика)

а) $$\left(39{,}96: (-3{,}7)-14{,}25\cdot 0{,}8\right)\cdot 0{,}1=-2{,}22.$$

$$39{,}96: (-3{,}7)=-10{,}8$$
$$14{,}25\cdot 0{,}8=11{,}4$$
$$-10{,}8-11{,}4=-22{,}2$$
$$-22{,}2\cdot 0{,}1=-2{,}22$$

б) $$25\frac{1}{6}-3\left(3\frac{1}{5}+2\frac{1}{4}\right)\cdot 5=-2\frac{1}{12}.$$

$$3\frac{1}{5}+2\frac{1}{4}=3\frac{4}{20}+2\frac{5}{20}=5\frac{9}{20}$$
$$5\frac{9}{20}\cdot 5=\frac{109}{20}\cdot 5=\frac{109}{4}=27\frac{1}{4}$$
$$25\frac{1}{6}-27\frac{1}{4}=25\frac{2}{12}-27\frac{3}{12}=-\left(27\frac{3}{12}-25\frac{2}{12}\right)=-2\frac{1}{12}$$

в) $$\frac{(18-2{,}64):1\frac{3}{5}}{\left(4\frac{3}{7}+1\frac{2}{3}\right)\cdot 2{,}1}=0{,}75.$$

$$18-2{,}64=15{,}36$$
$$15{,}36:1\frac{3}{5}=15{,}36:\frac{8}{5}=15{,}36\cdot \frac{5}{8}=9{,}6$$
$$4\frac{3}{7}+1\frac{2}{3}=4\frac{9}{21}+1\frac{14}{21}=5\frac{23}{21}=6\frac{2}{21}$$
$$6\frac{2}{21}\cdot 2{,}1=\frac{128}{21}\cdot \frac{21}{10}=12{,}8$$
$$9{,}6:12{,}8=\frac{96}{128}=\frac{3}{4}=0{,}75$$

Ответ: а) $$-2{,}22$$; б) $$-2\frac{1}{12}$$; в) $$0{,}75$$.