\(\frac{-7}{72}\) và \(\frac{9}{-40}\)
* \(\frac{9}{-40}=\frac{-9}{40}\)
Ta có : \(MSC=BCNN(72,40)=360\)
Quy đồng : \(\frac{-7}{72}=\frac{-7\cdot5}{72\cdot5}=\frac{-35}{360}\)
\(\frac{9}{-40}=\frac{-9}{40}=\frac{-9\cdot9}{40\cdot9}=\frac{-81}{360}\)
Mà \(\frac{-35}{360}>\frac{-81}{360}\Rightarrow\frac{-7}{72}>\frac{9}{-40}\)
Vậy : \(\frac{-7}{72}>\frac{9}{-40}\)