\(\frac{1}{2}+\frac{1}{2}=\frac{2}{2}=1\)

\(\frac{5}{4}+\frac{5}{4}=\frac{10}{4}=\frac{5}{2}\)

\(\frac{6}{6}+\frac{6}{6}=\frac{12}{12}=1\)

Tk mk vs nha m.n !! ^^

1;2,5;2 kết quả lần lượt

\(\frac{1}{2}:\frac{3}{2}:\frac{5}{4}:\frac{6}{5}:\frac{7}{6}:\frac{8}{7}\)

\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{7}\cdot\frac{7}{8}\)

\(=\frac{1\cdot\left(2\cdot5\cdot6\cdot7\right)}{8\cdot3\cdot\left(2\cdot5\cdot6\cdot7\right)}\)

\(=\frac{1}{24}\)

\(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{7}\cdot\frac{7}{8}\cdot\frac{8}{9}\cdot\frac{9}{10}\)

\(=\frac{1\cdot\left(2\cdot3\cdot4\cdot5\cdot6\cdot7\cdot8\cdot9\right)}{\left(2\cdot3\cdot4\cdot5\cdot6\cdot7\cdot8\cdot9\right)\cdot10}\)

\(=\frac{1}{10}\)

1. \(\frac{7}{8}\) và \(\frac{8}{7}\)

• \(7 \times 7 = 49\)
• \(8 \times 8 = 64\)
  ⇒ \(\frac{7}{8} < \frac{8}{7}\).

2. \(\frac{5}{6}\) và \(\frac{6}{5}\)

• \(5 \times 5 = 25\)
• \(6 \times 6 = 36\)
  ⇒ \(\frac{5}{6} < \frac{6}{5}\).

3. \(\frac{5}{9}\) và \(\frac{6}{9}\)

• Mẫu giống nhau, so tử: \(5 < 6\).
  ⇒ \(\frac{5}{9} < \frac{6}{9}\).

(Chú ý: bạn ghi “\(\frac{9}{5}\)” và “\(\frac{9}{6}\)” thì khác nhé, nhưng theo mình đọc thì là \(\frac{5}{9}\) và \(\frac{6}{9}\)). Bạn xác nhận lại?

4. \(\frac{7}{2}\) và \(\frac{5}{2}\)

• Mẫu giống nhau, so tử: \(7 > 5\).
  ⇒ \(\frac{7}{2} > \frac{5}{2}\).

5. \(\frac{8}{5}\) và \(\frac{8}{9}\)

• Cùng tử 8, so mẫu: \(5 < 9\) ⇒ phân số có mẫu nhỏ hơn thì lớn hơn.
  ⇒ \(\frac{8}{5} > \frac{8}{9}\).

6. \(\frac{12}{34}\) và \(\frac{12}{45}\)

• Cùng tử 12, so mẫu: \(34 < 45\) ⇒ phân số có mẫu nhỏ hơn thì lớn hơn.
  ⇒ \(\frac{12}{34} > \frac{12}{45}\).

✅ Kết quả:

\(\frac{7}{8} < \frac{8}{7} , \frac{5}{6} < \frac{6}{5} , \frac{5}{9} < \frac{6}{9} , \frac{7}{2} > \frac{5}{2} , \frac{8}{5} > \frac{8}{9} , \frac{12}{34} > \frac{12}{45} .\)

\(a.\frac{3}{7}.\frac{5}{6}+\frac{5}{6}.\frac{4}{7}=\left(\frac{3}{7}+\frac{4}{7}\right).\frac{5}{6}=1.\frac{5}{6}=\frac{5}{6}\)

\(b.\frac{1}{6}:\frac{4}{5}+\frac{1}{8}:\frac{4}{5}=\left(\frac{1}{6}+\frac{1}{8}\right):\frac{4}{5}=\left(\frac{4}{24}+\frac{3}{24}\right):\frac{4}{5}=\frac{7}{24}:\frac{4}{5}=\frac{7.5}{24.4}\)\(=\frac{35}{96}\)

\(c.\frac{1}{6}:\frac{4}{5}-\frac{1}{8}:\frac{4}{5}=\left(\frac{1}{6}-\frac{1}{8}\right):\frac{4}{5}=\left(\frac{4}{24}-\frac{3}{24}\right):\frac{4}{5}\)\(=\frac{1}{24}:\frac{4}{5}=\frac{1.5}{24.4}=\frac{5}{96}\)

a) \(\frac{3}{7}\cdot\frac{5}{6}+\frac{5}{6}\cdot\frac{4}{7}\)

\(=\left(\frac{3}{7}+\frac{4}{7}\right)\cdot\frac{5}{6}\)

\(=1\cdot\frac{5}{6}\)

\(=\frac{5}{6}\)

b) \(\frac{1}{6}:\frac{4}{5}+\frac{1}{8}:\frac{4}{5}\)

\(=\left(\frac{1}{6}+\frac{1}{8}\right):\frac{4}{5}\)

\(=\frac{7}{24}:\frac{4}{5}\)

\(=\frac{35}{96}\)

c) \(\frac{1}{6}:\frac{4}{5}-\frac{1}{8}:\frac{4}{5}\)

\(=\left(\frac{1}{6}-\frac{1}{8}\right):\frac{4}{5}\)

\(=\frac{1}{24}:\frac{4}{5}\)

\(=\frac{5}{96}\)

\(\frac{3}{4}+\frac{2}{3}=\frac{9}{12}+\frac{8}{12}=\frac{17}{12}\)

\(\frac{9}{2}-4=\frac{9}{2}-\frac{8}{2}=\frac{1}{2}\)

\(\frac{4}{5}\times\frac{3}{2}=\frac{4\times3}{5\times2}=\frac{12}{10}=\frac{6}{5}\)

\(\frac{5}{6}:\frac{6}{5}=\frac{5}{6}\times\frac{5}{6}=\frac{25}{36}\)

\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)

\(=1:\frac{5}{6}\)

\(=1\times\frac{6}{5}\)

\(=\frac{6}{5}\)

\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)

\(=1:\frac{5}{6}\)

\(=1\times\frac{6}{5}\)

\(=\frac{6}{5}\)

\(\frac{1}{6}+\frac{5}{6}=\frac{6}{6}=1\)

\(\frac{25}{5}+\frac{2}{6}=\frac{150}{30}+\frac{10}{30}=\frac{160}{30}=\frac{32}{6}=\frac{16}{3}\)

\(\frac{12}{5}+\frac{6}{9}=\frac{108}{45}+\frac{30}{45}=\frac{138}{45}\)

\(\frac{11}{6}\)

\(\frac{16}{3}\)

\(\frac{46}{3}\)

Chọn B

c) Các phân số được sắp xếp theo thứ tự từ lớn đến bé là:

A.\(\frac{5}{6};\frac{2}{3};\frac{4}{2}\)

B.\(\frac{4}{2};\frac{5}{6};\frac{2}{3}\)

C.\(\frac{2}{3};\frac{4}{2}:\frac{5}{6}\)

D.\(\frac{4}{2};\frac{2}{3};\frac{5}{6}\)

Khoanh B 

\(x+\frac{2}{3}=\frac{9}{11}\)

\(x=\frac{9}{11}-\frac{2}{3}\)

\(x=\frac{5}{33}\)

\(x-\frac{3}{10}=\frac{4}{15}\)

\(x=\frac{3}{10}-\frac{4}{15}\)

\(x=\frac{1}{10}\)

\(x\times\frac{1}{7}=\frac{5}{6}\)

\(x=\frac{5}{6}:\frac{1}{7}\)

\(x=\frac{35}{6}\)

\(x:\frac{3}{5}=\frac{1}{6}\)

\(x=\frac{3}{5}.\frac{1}{6}\)

\(x=\frac{1}{10}\)

+, \(x+\frac{2}{3}=\frac{9}{11}\)

\(x=\frac{9}{11}-\frac{2}{3}=\frac{5}{33}\)

+, \(x-\frac{3}{10}=\frac{4}{15}\)

\(x=\frac{4}{15}+\frac{3}{10}=\frac{17}{30}\)

+, \(x\cdot\frac{1}{7}=\frac{5}{6}\)

\(x=\frac{5}{6}:\frac{1}{7}=\frac{5}{6}.\frac{7}{1}=\frac{35}{6}\)

+,\(x:\frac{3}{5}=\frac{1}{6}\)

\(x=\frac{1}{6}\cdot\frac{3}{5}=\frac{3}{30}=\frac{1}{10}\)