219 Вправа 219Алгебра 8 клас Бевз 2025 · § 5 · стор. 50

219. Помнож дроби.

а) ${\displaystyle \frac{2}{3}\cdot \frac{5}{7}=}$${\displaystyle \frac{2\cdot 5}{3\cdot 7}=}$${\displaystyle \frac{10}{21}}$;

б) ${\displaystyle \frac{5}{2}\cdot \frac{4}{5a}=}$${\displaystyle \frac{5\cdot 4}{2\cdot 5a}=}$${\displaystyle \frac{\cancel{5}\cdot 2\cdot \cancel{2}}{\cancel{2}\cdot \cancel{5}a}=}$${\displaystyle \frac{2}{a}}$;

в) ${\displaystyle \frac{3}{-5}\cdot \frac{-3}{4}=}$${\displaystyle \frac{3\cdot (-3)}{-5\cdot 4}=}$${\displaystyle \frac{9}{20}}$;

г) ${\displaystyle \frac{x}{a}\cdot \frac{m}{2c}=}$${\displaystyle \frac{x\cdot m}{a\cdot 2c}=}$${\displaystyle \frac{xm}{2ac}}$;

ґ) ${\displaystyle \frac{3}{ab}\cdot \frac{5}{a{x}^2}=}$${\displaystyle \frac{3\cdot 5}{ab\cdot a{x}^2}=}$${\displaystyle \frac{15}{a^{2}b{x}^2}}$;

д) ${\displaystyle \frac{-1}{ab}\cdot \frac{-1}{ac}=}$${\displaystyle \frac{-1\cdot (-1)}{ab\cdot ac}=}$${\displaystyle \frac{1}{a^{2}bc}}$.