Tính hợp lí giúp mk với: 4) 3 5/7-5/7*4/15+(-5)/7*11/15. 8) 1/5-1/7+1/11 / 7/5-7/7+7/11 + 2/13+4/23-6/29 / 7/13-21/29+14/23. P/S: Ở câu 8, phép tính 1

Đáp án:

Giải thích các bước giải:

4) 3$\frac{5}{7}$ – $\frac{5}{7}$ . $\frac{4}{15}$ + $\frac{-5}{7}$ . $\frac{11}{15}$

= 3$\frac{5}{7}$ + $\frac{-5}{7}$ . $\frac{4}{15}$ + $\frac{-5}{7}$ . $\frac{11}{15}$

= 3$\frac{5}{7}$ + $\frac{-5}{7}$.($\frac{4}{15}$ + $\frac{11}{15}$)

= 3$\frac{5}{7}$ + $\frac{-5}{7}$.1

= 3$\frac{5}{7}$ + $\frac{-5}{7}$

= 3

8) $\frac{\frac{1}{5} – \frac{1}{7} + \frac{1}{11}}{\frac{7}{5} – \frac{7}{7} + \frac{7}{11}}$ +  $\frac{\frac{2}{13} – \frac{4}{23} + \frac{6}{29}}{\frac{7}{13} – \frac{21}{29} + \frac{14}{23}}$

= $\frac{1.(\frac{1}{5} – \frac{1}{7} + \frac{1}{11})}{7.(\frac{7}{5} – \frac{7}{7} + \frac{7}{11})}$ + $\frac{2.(\frac{1}{13} – \frac{2}{23} + \frac{3}{29})}{7.(\frac{1}{13} – \frac{3}{29} + \frac{2}{23})}$

= $\frac{1}{7}$ + $\frac{2}{7}$ 

= $\frac{3}{7}$