so sanh - 49 / 78 va 64 / -95
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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
=> \(\frac{-49}{78}\)< \(\frac{64}{-95}\)
lam cach nao the moi nguoi
sory em mới học lớp 5 thôi à