Rút gọn phân số

24/36=24:12/36:12=2/3

25/100=25:25/100:25=1/4

143/132=143:11/132:11=13/12

1326/1734=1326:102/1734:102=13/17

111111/131313=111111:10101/131313:10101=11/13

789789789/164164164=789789789:1001001/164164164:1001001=789/164

`25/40=(25:5)/(40:5)=5/8`

\(\dfrac{25}{40}\) = \(\dfrac{25:5}{40:5}\)= \(\dfrac{5}{8}\)

tổng số phần bằng nhau là :

`3+5=8 (phần)`

 tử số là : 

`40 : 8 xx 3= 15`

mẫu số là 

`40-15= 25`

vậy phân số đó là : `15/25`

➝3/5=a/b

=>5xa=3xb

=>5xa-3xb=0

mà a+b=40

ta suy ra a=15,b=25

=>phân số cần tìm là 15/25

vậy số cần tìm là 15/25

3/5=a/b

=>5xa=3xb

=>5xa-3xb=0

 a+b=40

ta suy ra a=15,b=25

=>phân số cần tìm là 15/25

`25/50=(25:25)/(50:25)=1/2`

`15/120=(15:15)/(120:15)=1/8`

`64/720=(64:16)/(720:16)=4/45`

`5/25=(5:5)/(25:5)=1/2`

`6/9=(6:3)/(9:3)=2/3`

`48/96=(48:48)/(96:48)=1/2`

`42/98=(42:14)/(98:14)= 3/7`

`18/30=(18:6)/(30:6)=3/5`

`80/240=(80:80)/(240:80)=1/3`

Bài 3:
\(\dfrac{25}{50}=\dfrac{25:25}{50:25}=\dfrac{1}{2}\)
\(\dfrac{15}{120}=\dfrac{15:15}{120:15}=\dfrac{1}{8}\)
\(\dfrac{64}{720}=\dfrac{64:16}{720:16}=\dfrac{4}{45}\)
\(\dfrac{5}{25}=\dfrac{5:5}{25:5}=\dfrac{1}{5}\)
\(\dfrac{6}{9}=\dfrac{6:3}{9:3}=\dfrac{2}{3}\)
\(\dfrac{48}{96}=\dfrac{48:48}{96:96}=\dfrac{1}{2}\)
\(\dfrac{42}{98}=\dfrac{42:14}{98:14}=\dfrac{3}{7}\)
\(\dfrac{18}{30}=\dfrac{18:6}{30:6}=\dfrac{3}{5}\)
\(\dfrac{80}{240}=\dfrac{80:80}{240:80}=\dfrac{1}{3}\)

\(\dfrac{120}{90}=\dfrac{4}{3}\)

\(\dfrac{39}{75}=\dfrac{13}{25}\)

\(\dfrac{225}{900}=\dfrac{1}{4}\)

120/90=4/3

39/75=13/25

225/900=1/4

\(\dfrac{120}{90}=\dfrac{120:30}{90:30}=\dfrac{4}{3}\)

\(\dfrac{39}{45}=\dfrac{39:3}{45:3}=\dfrac{13}{15}\)

\(\dfrac{225}{900}=\dfrac{225:15}{900:15}=\dfrac{17}{60}\)

\(\dfrac{10}{12}=\dfrac{10:2}{12:2}=\dfrac{5}{6}\\ \dfrac{48}{56}=\dfrac{48:8}{56:8}=\dfrac{6}{7}\\ \dfrac{18}{27}=\dfrac{18:9}{27:9}=\dfrac{2}{3}\\ \dfrac{27}{39}=\dfrac{27:3}{39:3}=\dfrac{9}{13}\)

\(\dfrac{2}{3}+\dfrac{2}{3}=\dfrac{2+2}{3}=\dfrac{4}{3}\)

\(\dfrac{2}{3}+\dfrac{2}{3}=\dfrac{2+2}{3}=\dfrac{4}{3}\)

vì đây là cộng cùng mẫu số nên ta cộng tử số với nhau giữ nguyên mẫu số

2/3+2/3=4/3💓💕💖💗💙💚💛💜💝💞💟❣💌

\(a.\dfrac{18}{45}=\dfrac{18:9}{45:9}=\dfrac{2}{5}\)

\(b,\dfrac{63}{81}=\dfrac{63:9}{81:9}=\dfrac{7}{9}\)

\(c,\dfrac{105}{325}=\dfrac{105:5}{325:5}=\dfrac{21}{65}\)

\(d,\dfrac{49}{56}=\dfrac{49:7}{56:7}=\dfrac{7}{8}\)

\(\dfrac{\text{18}}{45}=\dfrac{\text{18}:9}{45:9}=\dfrac{2}{5}\)

\(\dfrac{63}{81}=\dfrac{63:9}{81:9}=\dfrac{7}{9}\)

\(\dfrac{\text{105 }}{325}=\dfrac{\text{105 : 5}}{\text{325 : 5 }}=\dfrac{\text{21}}{\text{65 }}\)

\(\dfrac{\text{49}}{56}=\dfrac{\text{49}:7}{56:7}=\dfrac{7}{8}\)

a) \(\dfrac{18}{45}=\dfrac{18:18}{45:18}=\dfrac{2}{5}\)

b) \(\dfrac{63}{81}=\dfrac{63:63}{81:63}=\dfrac{7}{9}\)

c) \(\dfrac{105}{325}=\dfrac{105:105}{325:105}=\dfrac{21}{65}\)

d) \(\dfrac{49}{56}=\dfrac{49:49}{56:49}=\dfrac{7}{8}\)

`450/90 = (450:90)/(90:90) = 5`

`330/110 = (330:110)/(110:110) = 3`

`120/80 = (120:40)/(80:40) = 3/2`

`930/30 = (930 :30)/(30:30) = 31`

`750/150 = (750 :150)/(150:150) = 5`

450/90 = 5

330/110 = 3 

120/80 = 3/2

930/30 = 31

750/150 = 5

450/90 = 5

330/110 = 3

120/80 = 3/2

930/30 = 31

750/150 = 5

a)\(=\dfrac{12\times\left(4+6\right)}{2\times12}=\dfrac{10}{2}=5\)

b)\(=\dfrac{4\times4\times6}{2\times6\times4}=\dfrac{4}{2}=2\)

_{^{\(\dfrac{12\times4+12\times6}{24}=\dfrac{12\times\left(4+6\right)}{24}=\dfrac{12\times10}{24}=\dfrac{120}{24}=5\)}}

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

_{^{\(\dfrac{16\times8-16\times2}{12\times4}=\dfrac{16\times\left(8-2\right)}{12\times4}=\dfrac{16\times4}{12\times4}=\dfrac{4\times4\times4}{4\times3\times4}=\dfrac{4}{3}\)}}