a: =5/48+10/18=95/144

b: =3/4(7/5-1/2)=3/4x9/10=27/40

c: =2/3x35/24=70/72=35/36

a,C1 
 (5/6 + 5/8) x 2/3
= 35/24 x 2/3
=35/36
C2
 (5/6 + 5/8) x 2/3
= 5/6x2/3 + 5/8x2/3
= 10/18 + 10/24
= 35/36

b,C1
7/5 x 3/4 - 1/2 x 3/4
= 21/20 - 3/8
= 27/40
C2
7/5 x 3/4 - 1/2 x 3/4
=3/4 x (7/5-1/2)
=3/4x9/10
=27/40

a, 5/6 x (1/8x2/3) 

=5/6 x 1/12

=5/72

b,(7/5 - 1/2) x 3/4 

=0,9 x 3/4

=3,06

c,(5/6+5/8) x 2/3

=70/48 x 2/3

=35/36

a, 5/6 x (1/8x2/3) 

=5/6 x 1/12

=5/72

b,(7/5 - 1/2) x 3/4 

=0,9 x 3/4

=3,06

c,(5/6+5/8) x 2/3

=70/48 x 2/3

=35/36

trong sách giáo khoa hả

hnay mik cg hc 

Bài 3: 

a: x+3/8=14/9x10/35

\(\Leftrightarrow x+\dfrac{3}{8}=\dfrac{4}{9}\)

=>x=4/9-3/8=32/72-27/72=5/72

b: \(x-\dfrac{2}{7}=\dfrac{21}{10}\cdot\dfrac{15}{28}=\dfrac{21}{28}\cdot\dfrac{15}{10}=\dfrac{3}{4}\cdot\dfrac{3}{2}=\dfrac{9}{8}\)

\(\Leftrightarrow x=\dfrac{9}{8}+\dfrac{2}{7}=\dfrac{63}{56}+\dfrac{16}{56}=\dfrac{79}{56}\)

c: \(\dfrac{11}{7}-x=\dfrac{8}{3}\cdot\dfrac{9}{32}=\dfrac{1}{4}\cdot3=\dfrac{3}{4}\)

nên \(x=\dfrac{11}{7}-\dfrac{3}{4}=\dfrac{44}{28}-\dfrac{21}{28}=\dfrac{23}{28}\)

d: \(x+\dfrac{2}{5}=\dfrac{12}{35}\cdot\dfrac{14}{9}=\dfrac{4}{3}\cdot\dfrac{2}{5}=\dfrac{8}{15}\)

nên \(x=\dfrac{8}{15}-\dfrac{2}{5}=\dfrac{8}{15}-\dfrac{10}{15}=-\dfrac{2}{15}\)

a) C1

 \(\dfrac{1}{8}\times\dfrac{5}{6}+\dfrac{5}{6}\times\dfrac{2}{3}=\dfrac{5}{6}\times\left(\dfrac{1}{8}+\dfrac{2}{3}\right)=\dfrac{5}{6}\times\dfrac{19}{24}=\dfrac{95}{144}\)

   C2

\(\dfrac{1}{8}\times\dfrac{5}{6}+\dfrac{5}{6}\times\dfrac{2}{3}=\dfrac{5}{48}+\dfrac{10}{18}=\dfrac{95}{144}\)

b) C1

  \(\dfrac{7}{5}\times\dfrac{3}{4}-\dfrac{1}{2}\times\dfrac{3}{4}=\dfrac{3}{4}\times\left(\dfrac{7}{5}-\dfrac{1}{2}\right)=\dfrac{3}{4}\times\dfrac{9}{10}=\dfrac{27}{40}\)

    C2 

   \(\dfrac{7}{5}\times\dfrac{3}{4}-\dfrac{1}{2}\times\dfrac{3}{4}=\dfrac{21}{20}-\dfrac{3}{8}=\dfrac{27}{40}\)

c) C1

 \(\left(\dfrac{5}{6}+\dfrac{5}{8}\right)\times\dfrac{2}{3}=\dfrac{35}{24}\times\dfrac{2}{3}=\dfrac{35}{36}\)

  C2 

  \(\left(\dfrac{5}{6}+\dfrac{5}{8}\right)\times\dfrac{2}{3}=\left(\dfrac{5}{6}\times\dfrac{2}{3}\right)+\left(\dfrac{5}{8}\times\dfrac{2}{3}\right)=\dfrac{5}{9}+\dfrac{5}{12}=\dfrac{35}{36}\)

a: =5/6(1/8+2/3)=5/6*19/24=95/144

b: =3/4(7/5-1/2)=27/40

c: =35/24*2/3=35/36

a:\(=\left(\dfrac{3}{4}+\dfrac{2}{4}\right):\dfrac{3}{5}=\dfrac{5}{4}\cdot\dfrac{5}{3}=\dfrac{25}{12}\)

b: \(=\left(\dfrac{5}{6}-\dfrac{3}{6}\right):\dfrac{3}{2}=\dfrac{1}{3}\cdot\dfrac{2}{3}=\dfrac{2}{9}\)

`( 2/3 xx 4/5) xx 5/6`

`= 8/15 xx 5/6`

`= 40/90`

`=4/9`

__

`( 2/3 xx 4/5) xx 5/6`

`= 2/3 xx (4/5 xx 5/6)`

`= 2/3 xx 2/3`

`= 4/9`

-------

`(1/2 + 1/3) xx 1/5`

`= ( 3/6 +2/6) xx 1/5`

`= 5/6 xx1/5`

`= 5/30`

`=1/6`

__

`(1/2 + 1/3) xx 1/5`

`=1/2 xx 1/5 + 1/3 xx 1/5`

`= 1/10 + 1/15`

`=1/6`

a)

c1

`(2/3xx4/5)xx5/6`

`=8/15xx5/6`

`=4/9`

c2

`(2/3xx4/5)xx5/6`

`=2/3xx4/5xx5/6`

`=2/3xx5/6xx4/5`

`=5/9xx4/5`

`=4/9`

b)

c1

`(1/2+1/3)xx1/5`

`=(3/6+2/6)xx1/5`

`=5/6xx1/5`

`=1/6`

c2

`(1/2+1/3)xx1/5`

`=1/2xx1/5+1/3xx1/5`

`=1/10+1/15`

`=3/30+2/30`

`=5/30=1/6`

a) Cách 1 : (3/4 + 1/2) x 5/7

               = 5/4 x 5/7

                = 25/28

Cách 2 : (3/4 + 1/2) x 5/7

           = 3/4 x 5/7 + 1/2 x 5/7

            = 15/28 + 5/14

            = 25/28

b) Cách 1 : 5/7 x 13/21 + 2/7 x 13/21

= 65/147 + 26/147

= 13/21

Cách 2 : 5/7 x 13/21 + 2/7 x 13/21

= (5/7 + 2/7) x 13/21

= 1 x 13/21

= 13/21

câu c tự làm

8 /15 :2/3+7/15:2/3 =                                              tính bằng 2 cách nhé các bạn

Cách 1:6/8+4/8+5/7=10/8*5/7=50/56=25/28

Cách 2 :3/4*5/7+1/2*
5/7=15/28+10/28=25/28

Cái này thầy tôi đã chữa yên tâm

tham khảo

a) (33164 + 28528) : 4 = 

Cách 1: (33164 + 28528) : 4

= 61692 : 4

= 15423

Cách 2: (33164 + 28528) : 4

= 33164 : 4 + 28528 : 4

= 8291 + 7132

= 15423

b) (403494 - 16415) : 7 =

Cách 1: (403494 - 16415) : 7

= 387079 : 7

= 55297 Cách 2: (403494 - 16415) : 7

= 403494 : 7 - 16415 : 7

= 57642 - 2345

= 55297

Cách 1:

a)\(\left(33164+28528\right):4=15423\)

b)\(\left(403494-16415\right):7=55297\)

Cách 2:

a)\(\left(33164+28528\right):4=33164:4+28528:4=8291+7132=15423\)

b)\(\left(403494-16415\right):7=403494:7-16415:7=57642-2345=55297\)