câu A là 4 phần mấy?

1: Rút gọn

a) \(-\dfrac{33}{51}=\dfrac{-33:3}{51:3}=\dfrac{-11}{17}\)

b) \(\dfrac{156}{-168}=\dfrac{-156}{168}=\dfrac{-156:12}{168:12}=\dfrac{-13}{14}\)

c) \(\dfrac{-75}{-100}=\dfrac{75}{100}=\dfrac{75:25}{100:25}=\dfrac{3}{4}\)

2: Quy đồng mẫu:

a) \(-\dfrac{3}{8}\) và \(\dfrac{5}{4}\)

MSC: 8

\(-\dfrac{3}{8}=\dfrac{-3}{8}\)

\(\dfrac{5}{4}=\dfrac{5\cdot2}{4\cdot2}=\dfrac{10}{8}\)

b) \(\dfrac{-7}{6}\) ; \(\dfrac{5}{12}\) và \(-\dfrac{5}{6}\)

MSC: 12

\(-\dfrac{7}{6}=\dfrac{-7\cdot2}{6\cdot2}=\dfrac{-14}{12}\)

\(\dfrac{5}{12}=\dfrac{5}{12}\)

\(\dfrac{-5}{6}=\dfrac{-5\cdot2}{6\cdot2}=\dfrac{-10}{12}\)

\(\dfrac{4\times9}{5\times9}=\dfrac{36}{45};\dfrac{7\times5}{9\times5}=\dfrac{25}{45}\\ \dfrac{5\times2}{8\times2}=\dfrac{10}{16};\dfrac{15}{16}\\ \dfrac{1\times40}{6\times40}=\dfrac{40}{240};\dfrac{5\times30}{8\times30}=\dfrac{150}{240};\dfrac{4\times48}{5\times48}=\dfrac{192}{240}\)

a 10/15 và 12/15

b 10/12 , 11/12 và 9/12

c 21/24 và 10/24

a: \(MSC:24\\ \dfrac{1}{3}=\dfrac{1\times8}{3\times8}=\dfrac{8}{24};\dfrac{1}{4}=\dfrac{1\times6}{4\times6}=\dfrac{6}{24}\)

b: \(MSC:24\\ \dfrac{5}{12}=\dfrac{5\times2}{12\times2}=\dfrac{10}{24};\dfrac{7}{6}=\dfrac{7\times4}{6\times4}=\dfrac{28}{24}\)

Đây nè:

\(a,\dfrac{1}{3};\dfrac{1}{4}và\dfrac{1}{24}\)

\(\dfrac{1}{3}=\dfrac{1\times8}{3\times8}=\dfrac{8}{24};\dfrac{1}{4}=\dfrac{1\times6}{4\times6}=\dfrac{6}{24};\dfrac{1}{24}\)

\(b,\dfrac{5}{12};\dfrac{7}{6}và\dfrac{5}{24}\)

\(\dfrac{5}{12}=\dfrac{5\times2}{12\times2}=\dfrac{10}{24};\dfrac{7}{6}=\dfrac{7\times4}{6\times4}=\dfrac{28}{24};\dfrac{5}{24}\)

Giải hộ mình đi ạ rồi mình tích đúng cho 

a) \(\dfrac{4}{7}và\dfrac{5}{6}\)⇔ \(\dfrac{24}{42}và\dfrac{35}{42}\)

b) \(\dfrac{5}{14}và\dfrac{3}{8}\)⇔ \(\dfrac{20}{56}và\dfrac{21}{56}\)

c) \(\dfrac{9}{10}và\dfrac{7}{5}\)⇔ \(\dfrac{9}{10}và\dfrac{14}{10}\)

d) \(\dfrac{3}{5};\dfrac{5}{6}và\dfrac{7}{30}\)⇔ \(\dfrac{18}{30};\dfrac{25}{30}và\dfrac{7}{30}\)

Bài 2: 

a: 5/4<7/4

b: 2/3=34/51

9/17=27/51

mà 34>27

nên 2/3>9/17

Bài 3: 

a: 1/3+3/8=8/24+9/24=17/24

b: 7/6+5/18=21/18+5/18=26/18=13/9

Từng bài 1 thôi nhé

Bài 2: 

a: 5/4<7/4

b: 2/3=34/51

9/17=27/51

mà 34>27

nên 2/3>9/17

Bài 3: 

a: 1/3+3/8=8/24+9/24=17/24

\(\dfrac{9}{12}=\dfrac{135}{180}\)

\(\dfrac{7}{15}=\dfrac{84}{180}\)