1/ Ta có : \(\frac{212121}{353535}=\frac{3.7.10101}{5.7.10101}=\frac{3}{5}=\frac{42}{70}\)
\(\frac{131313}{141414}=\frac{13.10101}{14.10101}=\frac{13}{14}=\frac{65}{70}\)
Vì 42 < 65 => \(\frac{42}{70}<\frac{65}{70}\) => \(\frac{212121}{353535}<\frac{131313}{141414}\)