1) Ta có :  \(\frac{49}{28}=\frac{49:7}{28:7}=\frac{7}{4}\)

             \(\frac{85}{51}=\frac{85:17}{51:17}=\frac{5}{3}\)

             \(\frac{64}{96}=\frac{64:32}{96:32}=\frac{2}{3}\)

             \(\frac{1212}{3030}=\frac{1212:606}{3030:606}=\frac{2}{5}\)

             \(\frac{32032}{48048}=\frac{32032:16016}{48048:16016}=\frac{2}{3}\)

             \(\frac{1339}{1442}=\frac{1339:103}{1442:103}=\frac{13}{14}\)    

Bài 1 :

49/28 =7/4    85/51=5/3   64/96=2/3     1212/3030=2/5     32032/48048=2/3   1339/1442=13/14

85/153= 5/9

1111/1212= 11/12

1530/1632= 15/16

85/153= 5/9

1111/1212= 11/12

1530/1632= 15/16

121/143=11/13

1212/1414=6/7

123123/456456=123/456=41/152

\(\dfrac{121}{143}=\dfrac{11}{13}\) ;  \(\dfrac{1212}{1414}=\dfrac{6}{7}\) ;  \(\dfrac{123}{456}=\dfrac{41}{152}\)

a:\(\dfrac{12}{13}\)

b:\(\dfrac{12}{13}\)

c:\(\dfrac{121}{131}\)

Câu a: \(\dfrac{12}{13}\)

Câu b: \(\dfrac{12}{13}\)

Câu c: \(\dfrac{121}{121}\)

\(\frac{1339}{1442}=\frac{13}{14}\)

\(\frac{1212}{3030}=\frac{2}{5}\)

\(\frac{1339}{1442}=\frac{1300+39}{1400+42}=\frac{13\times100+13\times3}{14\times100+14\times3}=\frac{13\times\left(100+3\right)}{14\times\left(100+3\right)}=\frac{13}{14}\)\(\frac{13}{14}\)

\(\frac{1212}{3030}=\frac{1200+12}{3000+30}=\frac{12\times100+12}{30\times100+30}=\frac{12\times\left(100+1\right)}{30\times\left(100+1\right)}=\frac{12}{30}=\frac{2}{5}\)

a )   − 1212 − 2424 = ( − 1212 ) : ( − 1212 ) ( − 2424 ) : ( − 1212 ) = 1 2

b )   120120 − 240240 = 120120 : ( − 120120 ) − 240240 : ( − 120120 ) = − 1 2

c)  1313 − 1414 = 1313 : ( − 101 ) − 1414 : ( − 101 ) = − 13 14

a) \(\frac{6}{9}=\frac{6:3}{9:3}=\frac{2}{3}\)

b)\(\frac{10}{48}=\frac{10:2}{48:2}=\frac{5}{24}\)

c)\(\frac{72}{84}=\frac{72:12}{84:12}=\frac{6}{7}\)

d)\(\frac{1212}{3939}=\frac{1212:303}{3939:303}=\frac{4}{13}\)

#H

Rút gọn phân số:

\(\frac{6}{9}=\frac{6\div3}{9\div3}=\frac{2}{3}\)

\(\frac{10}{48}=\frac{10\div2}{48\div2}=\frac{5}{24}\)

\(\frac{72}{84}=\frac{72\div12}{84\div12}=\frac{6}{7}\)

\(\frac{1212}{3939}=\frac{1212\div303}{3939\div303}=\frac{4}{13}\)

\(\dfrac{205}{505}\) = \(\dfrac{205:5}{505:5}\) = \(\dfrac{41}{101}\)

\(\dfrac{1111}{1313}\) = \(\dfrac{1111:101}{1313:101}\) = \(\dfrac{11}{13}\)

\(\dfrac{1133}{1442}\) = \(\dfrac{1133:103}{1442:103}\) = \(\dfrac{11}{14}\)

\(\dfrac{2\times3\times4\times5}{3\times4\times5\times7}\) = \(\dfrac{3\times4\times5}{3\times4\times5}\) \(\times\) \(\dfrac{2}{7}\) = \(\dfrac{2}{7}\)

a) 33 66 = 33 : 33 66 : 33 = 1 2 b ) − 22 77 = − 22 : 11 77 : 11 = − 2 7

c ) 3030 6060 = 3030 : 3030 6060 : 3030 = − 1 2 d ) − 1212 − 2424 = ( − 1212 ) : ( − 1212 ) ( − 2424 ) : ( − 1212 ) = 1 2

e ) 120120 − 240240 = 120120 : ( − 120120 ) − 240240 : ( − 120120 ) = − 1 2

f ) 1313 − 1414 = 1313 : ( − 101 ) − 1414 : ( − 101 ) = − 13 14