Tử số chung là \(2^3.3^2.11=792\)

\(\dfrac{11}{13}=\dfrac{11x72}{13x72}=\dfrac{792}{936}\)

\(\dfrac{6}{8}=\dfrac{6x12x11}{8x12x11}=\dfrac{792}{1056}\)

\(\dfrac{4}{5}=\dfrac{4x18x11}{5x18x11}=\dfrac{792}{990}\)

\(\dfrac{8}{9}=\dfrac{8x9x11}{9x9x11}=\dfrac{792}{891}\)

\(\dfrac{9}{11}=\dfrac{9x8x11}{11x8x11}=\dfrac{792}{968}\)

11 = 1 \(\times\) 11; 6 = 2 \(\times\) 3; 8 = 2 \(\times\) 2  \(\times\) 2; 9 = 3 \(\times\) 3

Vậy tử số chung là: 11 \(\times\) 2 \(\times\)2 \(\times\) 2 \(\times\) 3 \(\times\) 3 = 792

\(\dfrac{11}{13}\) = \(\dfrac{11\times72}{13\times72}\) = \(\dfrac{792}{936}\)

\(\dfrac{6}{8}\) = \(\dfrac{6\times132}{8\times132}\) = \(\dfrac{792}{1056}\)

\(\dfrac{4}{5}\) = \(\dfrac{4\times198}{5\times198}\) = \(\dfrac{792}{990}\)

\(\dfrac{8}{9}\) = \(\dfrac{8\times99}{9\times99}\) = \(\dfrac{792}{891}\)

\(\dfrac{9}{11}\) = \(\dfrac{9\times88}{11\times88}\) = \(\dfrac{792}{968}\)

Bài 1: 

a: 3/4=54/72

-1/9=-8/72

-5/8=-45/72

b: -1/7=-8/56

-1/-8=1/8=7/56

3/4=42/56

Ta có: 

`11/10 = 1 + 1/10`

`7/6 = 1+1/6`

`10/9 = 1 + 1/9`

`9/8 = 1 + 1/8`

Ta có: `1/10 < 1/9 < 1/8 < 1/6`

nên `11/10 < 10/9  < 9/8 < 7/6`

`MSC: 63`

`3/7=(3xx9)/(7xx9)=27/63`

`4/9=(4xx7)/(9xx7)=28/63`

`8/21=(8xx3)/(21xx3)=24/63`

giúp tớ

Ta có: 
\(MSC:36\)
\(\dfrac{8}{9}=\dfrac{8\times4}{9\times4}=\dfrac{32}{36}\)
\(\dfrac{2}{4}=\dfrac{2\times9}{4\times9}=\dfrac{18}{36}\)

`MSC: 36`

\(\dfrac{8}{9}=\dfrac{8\times4}{9\times4}=\dfrac{32}{36}\)

\(\dfrac{2}{4}=\dfrac{2\times9}{4\times9}=\dfrac{18}{36}\)

MSC : 360

`5/8 = (5xx45)/(8xx45)=225/360`

`7/20=(7xx18)/(20xx18)=126/360`

`-4/9=(-4xx40)/(9xx40)=-160/360`

=50/180;63/180;-80/180

giúp mình với

a)\(\dfrac{7}{8}=\dfrac{7}{8};\dfrac{9}{8}=\dfrac{9}{8}\)

b)\(\dfrac{2}{3}=\dfrac{40}{60};\dfrac{3}{4}=\dfrac{45}{60};\dfrac{6}{5}=\dfrac{72}{60}\)

c)\(\dfrac{13}{12}=\dfrac{65}{60};\dfrac{5}{6}=\dfrac{50}{60};\dfrac{4}{5}=\dfrac{48}{60}\)

d)\(\dfrac{9}{8}=\dfrac{54}{48};\dfrac{7}{24}=\dfrac{14}{48};\dfrac{41}{48}=\dfrac{41}{48}\)

Máy mik bị mờ cam thông cảm

45/63 , 56/ 63

\(=\dfrac{5\times9}{7\times9};\dfrac{5\times7}{9\times7}\)

\(=\dfrac{45}{63};\dfrac{35}{63}\)

45/63,56/63

\(\dfrac{72}{90};\dfrac{48}{90};\dfrac{-135}{90};\dfrac{-900}{90};\dfrac{-70}{90}\)

Ta có: \(\dfrac{4}{5}=\dfrac{72}{90}\);\(\dfrac{8}{15}=\dfrac{48}{90}\);\(\dfrac{-3}{2}=\dfrac{-135}{90}\);\(\dfrac{-2}{10}=\dfrac{-18}{90}\);\(\dfrac{-7}{9}=\dfrac{-70}{90}\)