Ta có : \(\dfrac{3}{5}< 1;\dfrac{7}{9}< 1;\dfrac{4}{3}>1;\dfrac{9}{11}< 1\)
\(\Rightarrow\) Ta chỉ cần so sánh 3 phân số \(\dfrac{3}{5};\dfrac{7}{9};\dfrac{9}{11}\) nữa thôi .
Ta lại có : \(\dfrac{3}{5}\text{=}\dfrac{3\times11\times9}{5\times11\times9}\text{=}\dfrac{297}{495}\)
\(\dfrac{7}{9}\text{=}\dfrac{7\times5\times11}{9\times5\times11}\text{=}\dfrac{385}{495}\)
\(\dfrac{9}{11}\text{=}\dfrac{9\times5\times9}{11\times5\times9}\text{=}\dfrac{405}{495}\)
Do \(405>385>297\) nên \(\dfrac{405}{495}>\dfrac{385}{495}>\dfrac{297}{495}\) hay \(\dfrac{9}{11}>\dfrac{7}{9}>\dfrac{3}{5}\)
\(\Rightarrow\dfrac{3}{5};\dfrac{7}{9};\dfrac{9}{11};\dfrac{4}{3}\)
