Упр.792 ГДЗ Ткачёва 6 класс (Математика)

1. Найти значение выражения:
   
   1) $$\text{а}+\left(-2\frac{1}{6}\right)$$, если $$\text{а}=-1\frac{5}{8}$$; $$\text{а}=1\frac{1}{4}$$;
   
   2) $$a-\left(-3\frac{7}{12}\right)$$, если $$a=-1\frac{5}{18}$$; $$a=2\frac{5}{6}$$.

1) При $$a=-1\frac{5}{8}$$:

$$a+\left(-2\frac{1}{6}\right)=-1\frac{5}{8}+\left(-2\frac{1}{6}\right)$$
$$= -\left(1\frac{5}{8}+2\frac{1}{6}\right)$$
$$= -\left(1\frac{15}{24}+2\frac{4}{24}\right) = -3\frac{19}{24}$$

При $$a=1\frac{1}{4}$$:

$$a+\left(-2\frac{1}{6}\right)=1\frac{1}{4}+\left(-2\frac{1}{6}\right)$$
$$= -\left(2\frac{1}{6}-1\frac{1}{4}\right)$$
$$= -\left(2\frac{2}{12}-1\frac{3}{12}\right) = -\left(1\frac{14}{12}-1\frac{3}{12}\right) = -\frac{11}{12}$$

2) При $$a=-1\frac{5}{18}$$:

$$a-\left(-3\frac{7}{12}\right)=-1\frac{5}{18}+3\frac{7}{12}$$
$$=3\frac{7}{12}-1\frac{5}{18}$$
$$=3\frac{21}{36}-1\frac{10}{36} =2\frac{11}{36}$$

При $$a=2\frac{5}{6}$$:

$$a-\left(-3\frac{7}{12}\right)=2\frac{5}{6}+3\frac{7}{12}$$
$$=2\frac{10}{12}+3\frac{7}{12} =5\frac{17}{12} =6\frac{5}{12}$$

Ответ

1) $$-3\frac{19}{24}$$; $$-\frac{11}{12}$$.

2) $$2\frac{11}{36}$$; $$6\frac{5}{12}$$.