81. Решите уравнение: 2 6 3) x = 25; 1)x = =; 7 5 7 8 4) 6x = 1; 2)x=1; 4 5) x: 25 = 32 8 5 6) 4: x = 6 35

Ответ: 1) \[ \frac{7}{3} \]; 2) \[ \frac{11}{8} \]; 3) 30; 4) \[ \frac{1}{24} \]; 5) \[ \frac{5}{128} \]; 6) \[ \frac{15}{98} \]

Решим уравнения: 1) \[ \frac{6}{7} \]x = \[ \frac{2}{7} \] x = \[ \frac{2}{7} \] : \[ \frac{6}{7} \] x = \[ \frac{2}{7} \] \[ \times \] \[ \frac{7}{6} \] x = \[ \frac{2 \times 7}{7 \times 6} \] x = \[ \frac{14}{42} \] x = \[ \frac{1}{3} \] 2) \[ \frac{8}{11} \]x = 1 x = 1 : \[ \frac{8}{11} \] x = 1 \[ \times \] \[ \frac{11}{8} \] x = \[ \frac{11}{8} \] 3) \[ \frac{5}{6} \]x = 25 x = 25 : \[ \frac{5}{6} \] x = \[ \frac{25}{1} \] \[ \times \] \[ \frac{6}{5} \] x = \[ \frac{25 \times 6}{1 \times 5} \] x = \[ \frac{150}{5} \] x = 30 4) 6x = \[ \frac{1}{4} \] x = \[ \frac{1}{4} \] : 6 x = \[ \frac{1}{4} \] \[ \times \] \[ \frac{1}{6} \] x = \[ \frac{1}{24} \] 5) x : \[ \frac{8}{25} \] = \[ \frac{5}{32} \] x = \[ \frac{5}{32} \] \[ \times \] \[ \frac{8}{25} \] x = \[ \frac{5 \times 8}{32 \times 25} \] x = \[ \frac{40}{800} \] x = \[ \frac{1}{20} \] 6) 4 \[ \frac{2}{7} \] : x = \[ \frac{6}{35} \] \[ \frac{30}{7} \] : x = \[ \frac{6}{35} \] x = \[ \frac{30}{7} \] : \[ \frac{6}{35} \] x = \[ \frac{30}{7} \] \[ \times \] \[ \frac{35}{6} \] x = \[ \frac{30 \times 35}{7 \times 6} \] x = \[ \frac{1050}{42} \] x = 25

Ответ: 1) \[ \frac{1}{3} \]; 2) \[ \frac{11}{8} \]; 3) 30; 4) \[ \frac{1}{24} \]; 5) \[ \frac{1}{20} \]; 6) 25