Question

quy đồng rồi so sánh -21/45 , 14/21 , 18/48

Answer 1

\(-\frac{21}{45}=-\frac{2352}{5040}\)

\(\frac{14}{21}=\frac{3360}{5040}\)

\(\frac{18}{48}=\frac{1890}{5040}\)

Ta thấy: \(-\frac{2352}{5040}< \frac{1890}{5040}< \frac{3360}{5040}\)

Nên: \(-\frac{21}{45}< \frac{18}{48}< \frac{14}{21}\)

Mình nghĩ v đó

Answer 2

Rút gọn rồi quy đồng dễ hơn á ;-;

Ta có : \(\frac{-21}{45}=-\frac{7}{15}\); \(\frac{14}{21}=\frac{2}{3}\); \(\frac{18}{48}=\frac{3}{8}\)

Ta có BCNN(15,3,8) = 120

\(\Rightarrow\frac{-7}{15}=\frac{-7\cdot8}{15\cdot8}=\frac{-63}{120}\); \(\frac{2}{3}=\frac{2\cdot40}{3\cdot40}=\frac{80}{120}\); \(\frac{3}{8}=\frac{3\cdot15}{8\cdot15}=\frac{45}{120}\)

\(\Rightarrow-\frac{63}{120}< \frac{45}{120}< \frac{80}{120}\)

\(\Rightarrow-\frac{21}{45}< \frac{18}{48}< \frac{14}{21}\)

Answer 3

\(\frac{-21}{45}=\frac{-7}{15};\frac{14}{21}=\frac{2}{3};\frac{18}{48}=\frac{3}{8}\)

\(\frac{-7}{15}=\frac{-56}{120};\frac{2}{3}=\frac{80}{120};\frac{3}{8}=\frac{45}{120}\)

\(=>\frac{-56}{120}< \frac{45}{120}< \frac{80}{120}\)

\(=>\frac{-21}{45}< \frac{18}{48}< \frac{14}{21}\)