Bài `1:`
`a)` `2/7=\frac{2xx9}{7xx9}=18/63`
`5/9=\frac{5xx7}{9xx7}=35/63`
Vì `18<35` nên `18/63 < 35/63`
`=>` `2/7 < 5/9`
`b)` `2/3 = \frac{2xx3}{3xx3}=6/9`
`8/9` giữ nguyên
Vì `6<8` nên `6/9<8/9`
`=>` `2/3 < 8/9`
`c)` `7/20 =\frac{7xx3}{20xx3}=21/60`
`21/60` giữ nguyên
Vì `21=21` nên `21/60=21/60`
`=>` `7/20 = 21/60`
`d)` `8/13 = \frac{8xx86}{13xx86}=688/1118`
`13/86=\frac{13xx13}{86xx13}=169/1118`
Vì `688>169` nên `688/1118 > 169/1118`
`=>` `8/13 > 13/86`
Bài `2:`
`a)` `1/2 = \frac{1xx12}{2xx12}=12/24`
`1/3 =\frac{1xx8}{3xx8}=8/24`
`3/8 = \frac{3xx3}{8xx3}=9/24`
`=>` `1/2 ; 3/8 ; 1/3`
`b)` `5/24 ` giữ nguyên
`11/8 = \frac{11xx3}{8xx3}=33/24`
`10/12=5/6=\frac{5xx4}{6xx4}=20/24`
`=>` `11/24 ; 20/24;4/24`
`c)` `3/4=\frac{3xx10}{4xx10}=30/40`
`9/10=\frac{9xx4}{10xx4}=36/40`
`7/8=\frac{7xx5}{8xx5}=35/40`
`=>` `9/10;7/8;3/4`
`d)` `3/5 =\frac{3xx6}{5xx6}=18/30`
`1/3 =\frac{1xx10}{3xx10}=10/30`
`7/30` giữ nguyên
`=>` `3/5 ; 1/3 ; 7/30`
