12 mình chịu

11/15 + 8/5=                   Tính phân số

6/7 - 5/21=

25/4 x 16/100

7 x 2/49 =

4/3 : 2/9

5/8 : 25 =

đây là kết quả của mình nhé .

21/32

2/9

7/10

1/15

21/32

2/9

7/10

1/15

\(\dfrac{7}{4}:\dfrac{8}{3}=\dfrac{21}{32}\)

\(\dfrac{7}{6}:\dfrac{21}{4}=\dfrac{28}{126}\)

\(\dfrac{8}{5}:\dfrac{16}{7}=\dfrac{56}{80}\)

\(\dfrac{5}{12}:\dfrac{25}{4}=\dfrac{20}{300}\)

Có gì you tự rút gọn nha :>

a)    \(\frac{3}{16}+\frac{4}{15}+\frac{5}{16}+\frac{1}{15}\)

\(=\left(\frac{3}{16}+\frac{5}{16}\right)+\left(\frac{4}{15}+\frac{1}{15}\right)\)

\(=\frac{1}{2}+\frac{1}{3}\)

\(=\frac{5}{6}\)

b)   \(\frac{6}{7}\times\frac{8}{15}\times\frac{7}{6}\times\frac{15}{16}\)

\(=\left(\frac{6}{7}\times\frac{7}{6}\right)\times\left(\frac{8}{15}\times\frac{15}{16}\right)\)

\(=1\times\frac{1}{2}=\frac{1}{2}\)

c)   \(\frac{19}{20}\times\frac{13}{21}+\frac{9}{20}\times\frac{8}{21}\)

\(=\frac{19\times13}{20\times21}+\frac{9\times8}{20\times21}\)

\(=\frac{247}{420}+\frac{72}{420}\)

\(=\frac{319}{420}\)

còn phần D đâu bn 

tích cho chị nha

 câu a)     = 5/6

 câu b = 1/2

 câu c = 319/420

7/4 : 8/3 = 7/4 x 3/8 = 21/32

7/6 : 21/4 = 7/6 x 4/21= 2/9

8/ 5 : 16/7 = 8/5 x 7/16 = 7/10

5/12 : 25/4 = 5/12 x 4/24 = 1/15

21/32

2/9 

7/10

1/15

21/32

2/9 

7/10

1/15

a. -3/4 x 12/-5 x (-25/6)=-15/2

b. -2 x -38/21 x -7/4 x (-3/8)=-19/8

c. (11/12: 33/16) x 3/5=4/15

d. 7/23 x [(-8/6)- 45/18]=-7/6

a. -3/4 x 12/-5 x (-25/6)=-15/2

b. -2 x -38/21 x -7/4 x (-3/8)=-19/8

c. (11/12: 33/16) x 3/5=4/15

d. 7/23 x [(-8/6)- 45/18]=-7/6

= 3/4 : 5/8 = 6/5

\(\dfrac{4}{7}\times\dfrac{21}{16}:\dfrac{5}{8}\)

\(=\dfrac{3}{4}:\dfrac{5}{8}=\dfrac{6}{5}\)

6/5

1.\(\dfrac{8}{11}+\dfrac{8}{33}\times\dfrac{3}{4}=\dfrac{8}{11}+\dfrac{8\times3}{33\times4}=\dfrac{8\times12}{11\times12}+\dfrac{8\times3}{33\times4}=\dfrac{8\times15}{132}=\dfrac{120}{132}=\dfrac{10}{11}\)

2.\(\dfrac{7}{9}\times\dfrac{3}{14}:\dfrac{5}{8}=\dfrac{7}{9}\times\dfrac{3}{14}\times\dfrac{8}{5}=\dfrac{4}{15}\)

3.\(\dfrac{5}{12}-\dfrac{7}{32}:\dfrac{21}{16}=\dfrac{5}{12}-\dfrac{7}{32}\times\dfrac{16}{21}=\dfrac{5}{12}-\dfrac{1}{6}=\dfrac{5-2}{12}=\dfrac{3}{12}=\dfrac{1}{4}\)

`@V.Tr.V`

`8/11+8/33xx3/4=8/11+2/11=10/11`

`7/9xx3/14:5/8=7/9xx3/14xx8/5=[7xx3xx4xx2]/[3xx3xx7xx2xx5]=4/[3xx5]=4/15`

`5/12-7/32:21/16=5/12-7/32xx16/21=5/12-2/12=3/12=1/4`

8/11 + 8/33 x 3/4 = 8/11 + 2/11 = 10/11

7/9 x 3/14 : 5/8 = 1/6 : 5/8 = 4/15

5/12 - 7/32 : 21/16 = 5/12 - 1/6 = 1/4

= 4/7 x 21/16 x 8/5 

= 3/4 x 8/5

= 6/5

=3/4:5/8=6/5