Ta có :\(\dfrac{5}{15}\)=\(\dfrac{40}{120}\)
\(\dfrac{12}{8}=\dfrac{180}{120}\)
Vì ; 40<180 nên \(\dfrac{40}{120}< \dfrac{180}{120}\)
\(\Rightarrow\)\(\dfrac{5}{15}< \dfrac{12}{8}\)
\(c_2\) Ta có :\(\dfrac{5}{15}\)\(< 1\)
\(\dfrac{12}{8}>1\)
\(\Rightarrow\)\(\dfrac{5}{15}< \dfrac{12}{8}\)