Упр.792 ГДЗ Ткачёва 6 класс (Математика)

1) а + (-2 1/6), если а = -1 5/8; а = 1 1/4;
2) a — (-3 7/12), если a = -1 5/18; a = 2 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) $$2\frac{11}{36}$$; $$6\frac{5}{12}$$.