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

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

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

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

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

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`

`(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:

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

1/4*1/2+1/6*1/2=1/8+1/12=20/96                                  C2     ( 1/4+1/6)*1/2

                                                                                             =10/24*1/2=10/48

b,(3/2-2/5)*1/3=11/10*1/3                                                 C2    3/2*1/3+2/5*1/3

                                                                                                  =3/6+2/15=     53/90

=11/30

\(\left(\frac{1}{4}+\frac{1}{6}\right)x\frac{1}{2}\)                                                           \(\left(\frac{3}{2}-\frac{2}{5}\right)x\frac{1}{3}\)

\(c1:=\frac{5}{12}x\frac{1}{2}=\frac{5}{24}\)                                                   \(c1:\frac{11}{10}x\frac{1}{3}=\frac{11}{30}\)

\(c2:=\frac{1}{4}x\frac{1}{2}+\frac{1}{6}x\frac{1}{2}\)                                              \(c2:\frac{3}{2}x\frac{1}{3}-\frac{2}{5}x\frac{1}{3}\)

\(=\frac{1}{8}+\frac{1}{12}=\frac{12}{96}+\frac{8}{96}=\frac{20}{96}=\frac{5}{24}\)                         \(=\frac{1}{2}-\frac{2}{15}=\frac{11}{30}\)

CHÚC BẠN HỌC GIỎI

Ai giải giúp mình bài toán này nhé tối nay mình cần rồi ạ!

Tính bằng hai cách

A) (2/3×4/5)×5/6

B) (1/2+1/3)×1/5

nhanh lên

a: \(=\dfrac{3}{22}\cdot22\cdot\dfrac{3}{11}=3\cdot\dfrac{3}{11}=\dfrac{9}{11}\)

b: \(=\dfrac{5}{6}\cdot\dfrac{2}{5}=\dfrac{1}{3}\)

c: \(=\dfrac{17}{21}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{17}{21}\)

a : = \(\dfrac{3}{22}\). 22 . \(\dfrac{3}{11}\) = 3 . \(\dfrac{3}{11}\) = \(\dfrac{9}{11}\)

b : = \(\dfrac{5}{6}\). \(\dfrac{2}{5}\) = \(\dfrac{1}{3}\)

c: = \(\dfrac{17}{21}\)(\(\dfrac{3}{5}\) + \(\dfrac{2}{5}\)   ) = \(\dfrac{17}{21}\)

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

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

`= 1/2 xx ( 5/15 +3/15)`

`= 1/2 xx 8/15`

`= 8/30`

`=4/15`

__

`1/3 xx 1/2 - 1/5 xx 1/2`

`= 1/2 xx (1/3 -1/5)`

`= 1/2 xx ( 5/15 -3/15)`

`=1/2 xx 2/15`

`= 2/30`

`=1/15`

a)

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

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

`=1/2xx(5/15+3/15)`

`=1/2xx8/15`

`=4/15`

b)

`1/3xx1/2-1/5xx1/2`

`=1/2xx(1/3-1/5)`

`=1/2xx(5/15-3/15)`

`=1/2xx2/15`

`=1/15`

a)

$1/3xx1/2+1/2xx1/5$

$=1/2xx(1/3+1/5)$

$=1/2xx(5/15+3/15)$

$=1/2xx8/15$

$=4/15$

b)

$1/3xx1/2-1/5xx1/2$

$=1/2xx(1/3-1/5)$

$=1/2xx(5/15-3/15)$

$=1/2xx2/15$

$=1/15$

a) 2/3 : 3/5 × 5/7 : 2/3

= 2/3 × 5/3 × 5/7 × 3/2 

= 25/21

b) 1 1/2 × 1 1/3 × 1 1/18 × 1 1/15 × 1 1/24 × 1 1/35

= 3/2 × 4/3 × 19/18 × 16/15 × 25/24 × 36/35

= 2 × 152/35 × 15/14

= 304/35 × 15/14

= 152/7

Bài 3 là hỗn số hả em?