64° Вправа 64Алгебра 8 клас Тарасенкова 2025 · § 1 · стор. 20

64. Знайдіть значення виразів за таблицею 2.

Заповнена таблиця:

Обчислення.

1) ${\displaystyle a=}$${\displaystyle 1}$, ${\displaystyle b=}$${\displaystyle 2}$:

${\displaystyle (1-2):(1+2)=}$${\displaystyle -1:3=}$${\displaystyle -\frac{1}{3}}$;

${\displaystyle \frac{1+2\cdot 2}{2-1}=}$${\displaystyle \frac{5}{1}=}$${\displaystyle 5}$;

${\displaystyle \frac{1-2\cdot 2}{4+1}=}$${\displaystyle \frac{-3}{5}=}$${\displaystyle -0,6}$;

2) ${\displaystyle a=}$${\displaystyle 2}$, ${\displaystyle b=}$${\displaystyle 0,5}$:

${\displaystyle (2-0,5):(2+0,5)=}$${\displaystyle 1,5:2,5=}$${\displaystyle \frac{15}{25}=}$${\displaystyle \frac{3}{5}=}$${\displaystyle 0,6}$;

${\displaystyle \frac{2+2\cdot 0,5}{0,5-2}=}$${\displaystyle \frac{3}{-1,5}=}$${\displaystyle -2}$;

${\displaystyle \frac{2-2\cdot 0,5}{4+2}=}$${\displaystyle \frac{1}{6}=}$${\displaystyle \frac{1}{6}}$;

3) ${\displaystyle a=}$${\displaystyle 3}$, ${\displaystyle b=}$${\displaystyle -\frac{1}{2}}$:

${\displaystyle (3-\frac{1}{2}):(3+(-\frac{1}{2}))=}$${\displaystyle \frac{7}{2}:\frac{5}{2}=}$${\displaystyle \frac{7}{\underset{1}{\cancel{2}}}\cdot \frac{\stackrel{1}{\cancel{2}}}{5}=}$${\displaystyle \frac{7}{5}=}$${\displaystyle 1,4}$;

${\displaystyle \frac{3+2\cdot (-\frac{1}{2})}{-\frac{1}{2}-3}=}$${\displaystyle \frac{3-1}{-3,5}=}$${\displaystyle -\frac{2}{3,5}=}$${\displaystyle -\frac{20}{35}=}$${\displaystyle -\frac{4}{7}}$;

${\displaystyle \frac{3-2\cdot (-\frac{1}{2})}{4+3}=}$${\displaystyle \frac{3+1}{7}=}$${\displaystyle \frac{4}{7}}$;

4) ${\displaystyle a=}$${\displaystyle 5}$, ${\displaystyle b=}$${\displaystyle 10}$:

${\displaystyle (5-10):(5+10)=}$${\displaystyle -5:15=}$${\displaystyle -\frac{1}{3}}$;

${\displaystyle \frac{5+2\cdot 10}{10-5}=}$${\displaystyle \frac{25}{5}=}$${\displaystyle 5}$;

${\displaystyle \frac{5-2\cdot 10}{4+5}=}$${\displaystyle \frac{-15}{9}=}$${\displaystyle -\frac{5}{3}=}$${\displaystyle -1\frac{2}{3}}$.