Rút gọn phân số

\(\dfrac{18}{28}=\dfrac{18:2}{28:2}=\dfrac{9}{14}\)

\(\dfrac{39}{65}=\dfrac{39:13}{65:13}=\dfrac{3}{5}\)

39/65 = 39/65 : 13/13 = 3/5

\(\dfrac{34}{50}=\dfrac{34:2}{50:2}=\dfrac{17}{25}\)

\(\dfrac{48}{68}=\dfrac{48:4}{68:4}=\dfrac{12}{17}\)

\(\dfrac{78}{24}=\dfrac{78:6}{24:6}=\dfrac{13}{4}\)

\(\dfrac{112}{140}=\dfrac{112:28}{140:28}=\dfrac{4}{5}\)

\(\dfrac{12}{28}\)

\(\dfrac{12}{28}\)

6/14;12/28

\(\dfrac{30}{100}=\dfrac{30:10}{100:10}=\dfrac{3}{10}\)

\(\dfrac{55}{77}=\dfrac{55:11}{77:11}=\dfrac{5}{7}\)

\(\dfrac{234}{765}=\dfrac{234:9}{765:9}=\dfrac{26}{85}\)

\(\dfrac{8}{10000}=\dfrac{8:8}{10000:8}=\dfrac{1}{1250}\)

\(\dfrac{65}{117}=\dfrac{65:13}{117:13}=\dfrac{5}{9}\)

\(\dfrac{152}{114}=\dfrac{152:38}{114:38}=\dfrac{4}{3}\)

\(\dfrac{15}{125}=\dfrac{3}{25}\)

\(\dfrac{15}{125}=\dfrac{15:5}{125:5}=\dfrac{3}{25}\)

Bài `1`

`a, 36/72=(36:36)/(72:36)= 1/2`

`b,15/125=(15:5)/(125:5)=3/25`

Bài `2`

`a, MSC:36`

`4/9=(4xx4)/(9xx4)=16/36`

`5/4=(5xx9)/(4xx9)=45/36`

`b,MSC:100`

`25/100` giữ nguyên

`20/50=(20xx2)/(50xx2)=40/100`

`c,MSC:45`

`5/9=(5xx5)/(9xx5)=25/45`

`4/5=(4xx9)/(5xx9)=36/45`

`5/3=(5xx15)/(3xx15)=75/45`

sos

\(1.\\ a,\dfrac{36}{72}=\dfrac{36:36}{72:36}=\dfrac{1}{2}\\ b,\dfrac{15}{125}=\dfrac{15:5}{125:5}=\dfrac{3}{25}\\2.\\ a,\dfrac{4}{9}=\dfrac{4\times4}{9\times4}=\dfrac{16}{36}\\ \dfrac{5}{4}=\dfrac{5\times9}{4\times9}=\dfrac{45}{36}\\ b,\dfrac{25}{100}giữnguyên\\ \dfrac{20}{50}=\dfrac{20\times2}{50\times2}=\dfrac{40}{100}\\ c,\dfrac{5}{9}=\dfrac{5\times5}{9\times5}=\dfrac{25}{45}\\ \dfrac{4}{5}=\dfrac{4\times9}{5\times9}=\dfrac{36}{45}\\ \dfrac{5}{3}=\dfrac{5\times15}{3\times15}=\dfrac{75}{45}\)

\(\dfrac{50}{70}=\dfrac{50:10}{70:10}=\dfrac{5}{7}\)
\(\dfrac{24}{120}=\dfrac{24:24}{120:24}=\dfrac{1}{5}\)

\(\dfrac{50}{70}=\dfrac{5}{7}\\ \dfrac{24}{120}=\dfrac{1}{5}\)

50/70=50:10/70:10=5/7

24/120=24:24/120:24=1/5