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

`(1/3 + 1/5) xx 1/4`

`= ( 5/15 + 3/15) xx 1/4`

`= 8/15 xx 1/4`

`= 8/60`

`= 2/15`

__

`(1/3 + 1/5) xx 1/4`

`= 1/3 xx 1/4 + 1/5 xx 1/4`

`= 1/12 +1/20`

`=2/15`

\(C_1:\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{1}{4}\times\dfrac{1}{3}+\dfrac{1}{4}\times\dfrac{1}{5}=\dfrac{1}{12}+\dfrac{1}{20}=\dfrac{2}{15}\)

\(C_2:\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{8}{15}\times\dfrac{1}{4}=\dfrac{8\times1}{15\times4}=\dfrac{8}{60}=\dfrac{2}{15}\)

Cách 1:

\(\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\left(\dfrac{5}{15}+\dfrac{3}{15}\right)\times\dfrac{1}{4}=\dfrac{8}{15}\times\dfrac{1}{4}=\dfrac{8}{60}=\dfrac{2}{15}\)

Cách 2:

\(\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{5}\times\dfrac{1}{4}=\dfrac{1}{12}+\dfrac{1}{20}=\dfrac{5}{60}+\dfrac{3}{60}=\dfrac{8}{60}=\dfrac{2}{15}\)

82/15

Cách 1 : ( 7/5 x2 ) + ( 4/3 x 2 )

 =       14/5     +     8/3

 =            82/15

Cách 2 : ( 7/5 +4/3) x 2

 =        41/15     x 2

 =             82/15

a: =3/4*3/2+1/4*2

=3/8+1/2

=3/8+4/8=7/8

b: =4,1:0,15=82/3

Cách 1:

(1/4 + 2/3) x 4/5

= (3/12 + 8/12) x 4/5

= 11/12 x 4/5

= 44/60

= 11/15

Cách 2:

(1/4 + 2/3) x 4/5

= 1/4 x 4/5 + 2/3 x 4/5

= 4/20 + 8/15

=1/5 + 8/15

= 3/15 + 8/15

= 11/15

\(a,\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{8}{15}\times\dfrac{1}{4}=\dfrac{8}{60}=\dfrac{2}{15}\)

\(\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{5}\times\dfrac{1}{4}=\dfrac{1}{12}+\dfrac{1}{20}=\dfrac{20}{240}+\dfrac{12}{240}=\dfrac{32}{240}=\dfrac{2}{15}\)

\(b,\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}=\dfrac{2}{5}\times\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\times1=\dfrac{2}{5}\)

\(\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}=\dfrac{6}{35}+\dfrac{8}{35}=\dfrac{14}{35}=\dfrac{2}{5}\)

trả lời nhanh nha! trả lời trong tối hôm nay 19/3/2023 ạ

C1 : `a)(1/3+1/5)xx1/4`

`=(5/15+3/15)xx1/4`

`=8/15xx1/4`

`=8/60`

`=2/15`

__

C2: `a)(1/3+1/5)xx1/4`

`=1/3xx1/4+1/5xx1/4`

`=1/12+1/20`

`=5/60+3/60`

`=8/60`

`=2/15`

_________________

C1: `b)2/5xx3/7+2/5xx4/7`

`=6/35+8/35`

`=14/35`

`=2/5`

__

C2: `b)2/5xx3/7+2/5xx4/7`

`=2/5xx(3/7+4/7)`

`=2/5xx7/7`

`=2/5xx1`

`=2/5`

= 5/12

Cách 1:

\(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\times\dfrac{4}{9}\)

\(=\dfrac{5}{9}\times\dfrac{4}{9}\)

\(=\dfrac{20}{81}\)

Cách 2:

\(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\times\dfrac{4}{9}\)

\(=\dfrac{1}{3}\times\dfrac{4}{9}+\dfrac{2}{9}\times\dfrac{4}{9}\)

\(=\dfrac{4}{27}+\dfrac{8}{81}\)

\(=\dfrac{20}{81}\)

C1: \(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\)x\(\dfrac{4}{9}\)=\(\left(\dfrac{3}{9}+\dfrac{2}{9}\right)\text{x}\dfrac{4}{9}\)=\(\dfrac{5}{9}\text{x}\dfrac{4}{9}=\dfrac{20}{81}\)

C2: \(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\)x\(\dfrac{4}{9}\)=\(\dfrac{1}{3}\text{ x}\dfrac{4}{9}+\dfrac{2}{9}\text{ x}\dfrac{4}{9}\)=\(\dfrac{4}{27}+\dfrac{8}{81}=\dfrac{12}{81}+\dfrac{8}{81}=\dfrac{20}{81}\)

 \(C1:\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\times\dfrac{4}{9}\\ =\dfrac{5}{9}\times\dfrac{4}{9}\\ =\dfrac{20}{81}\)

\(C2:\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\times\dfrac{4}{9}\\ =\dfrac{1}{3}\times\dfrac{4}{9}+\dfrac{2}{9}\times\dfrac{4}{9}\\ =\dfrac{4}{27}+\dfrac{8}{81}\\ =\dfrac{20}{81}\)