vì 1999/2001 <1 ;1<12/11 suy ra 1999/2001<12/11
\(\frac{1999}{2001}\)và\(\frac{12}{11}\)
Vì\(\frac{1999}{2001}< 1;\frac{12}{11}>1\)
\(\Rightarrow\frac{11}{12}>\frac{1999}{2001}\)
Ta có :
\(\frac{1999}{2001}< 1\)
\(\frac{12}{11}>1\)
\(\Rightarrow\frac{1999}{2001}< \frac{12}{11}\)