a) Ta có:

+) \(\dfrac{1}{2}=\dfrac{3}{6}\)

+) \(\dfrac{1}{3}=\dfrac{2}{6}\)

+) \(\dfrac{2}{3}=\dfrac{4}{6}\)

=> \(\dfrac{2}{6}< \dfrac{3}{6}< \dfrac{4}{6}\)

hay \(\dfrac{1}{3}< \dfrac{1}{2}< \dfrac{2}{3}\)

b) Ta có:

+) \(\dfrac{4}{9}=\dfrac{56}{126}\)

+) \(-\dfrac{1}{2}=-\dfrac{63}{126}\)

+) \(\dfrac{3}{7}=\dfrac{54}{126}\)

=> \(-\dfrac{63}{126}< \dfrac{54}{126}< \dfrac{56}{126}\)

hay \(-\dfrac{1}{2}< \dfrac{3}{7}< \dfrac{4}{9}\)

c) Ta có:

+) \(\dfrac{27}{82}=\dfrac{2025}{6150}\)

+) \(\dfrac{26}{75}=\dfrac{2132}{6150}\)

=> \(\dfrac{2025}{6150}< \dfrac{2132}{6150}\)

hay \(\dfrac{27}{82}< \dfrac{26}{75}\)

d) Ta có:

+) \(-\dfrac{49}{78}=-\dfrac{4655}{7410}\)

+) \(-\dfrac{64}{95}=-\dfrac{4992}{7410}\)

=> \(-\dfrac{4665}{7410}>-\dfrac{4992}{7410}\)

hay \(-\dfrac{49}{78}>-\dfrac{64}{95}\)

Ta có \(\dfrac{-49}{78}\)và\(\dfrac{-64}{95}\)

\(\dfrac{-49}{78}\)\(=\dfrac{-49.95}{78.95}=\dfrac{-4655}{7410}\)

\(\dfrac{-64}{95}=\dfrac{-64.78}{95.78}=\dfrac{-4992}{7410}\)

Vì -4655 > -4992 \(=>\dfrac{-4655}{7410}>\dfrac{-4992}{7410}\)

\(=>\dfrac{-49}{78}>\dfrac{64}{-95}\)

Ta có -49.(-95) = 4655 < 4992 = 64.78

=> \(\frac{-49}{78}\)< \(\frac{64}{-95}\)

\(\dfrac{-49}{78}< \dfrac{64}{-95}\)

bó tay

tớ cũng đang đăng câu hỏi nè

bạn dùng phần bù nha: -49<64; 78>-95 kìa