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

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: \(=\dfrac{3\cdot2+5}{10}\cdot\dfrac{4}{5}=\dfrac{11}{10}\cdot\dfrac{4}{5}=\dfrac{44}{50}=\dfrac{22}{25}\)

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

3228

3228 nhé em

thanks

a: \(=\left(\dfrac{5}{8}-\dfrac{28}{8}\right)\cdot\dfrac{5}{6}=\dfrac{-23}{8}\cdot\dfrac{5}{6}=\dfrac{-115}{48}\)

b: \(=\dfrac{4}{7}\cdot\dfrac{24+25}{15}=\dfrac{4}{7}\cdot\dfrac{49}{15}=\dfrac{28}{15}\)

c: \(=\dfrac{7}{2}:\dfrac{24-10}{15}=\dfrac{7}{2}\cdot\dfrac{15}{14}=\dfrac{15}{4}\)

a, C₁:`6/7xx(2/5+3/10)=6/7xx7/10=3/5`

C₂:`6/7xx(2/5+3/10)=6/7xx2/5+6/7xx3/10=12/35+9/35=21/35=3/5`

b, C₁:`2/5xx3/7+2/5xx4/7=6/35+8/35=14/35=2/5`

C₂:`2/5xx3/7+2/5xx4/7=2/5xx(3/7+4/7)=2/5xx7/7=2/5xx1=2/5`

a: Cách 1: \(\left(\frac58-\frac72\right):\frac65\)

\(=\left(\frac58-\frac{28}{8}\right):\frac65\)

\(=-\frac{23}{8}\cdot\frac56=\frac{-115}{48}\)

Cách 2: \(\left(\frac58-\frac72\right):\frac65\)

\(=\left(\frac58-\frac72\right)\cdot\frac56\)

\(=\frac58\cdot\frac56-\frac72\cdot\frac56\)

\(=\frac{25}{48}-\frac{35}{12}\)
\(=\frac{25}{48}-\frac{140}{48}=\frac{-115}{48}\)

b: Cách 1: \(\frac47\left(\frac85+\frac53\right)\)

\(=\frac47\cdot\frac85+\frac47\cdot\frac53\)

\(=\frac{32}{35}+\frac{20}{21}\)

\(=\frac{96}{105}+\frac{100}{105}=\frac{196}{105}=\frac{28}{15}\)

Cách 2: \(\frac47\left(\frac85+\frac53\right)\)

\(=\frac47\left(\frac{24}{15}+\frac{25}{15}\right)\)

\(=\frac47\cdot\frac{49}{15}\)

\(=\frac{49}{7}\cdot\frac{4}{15}=7\cdot\frac{4}{15}=\frac{28}{15}\)

c: Cách 1: \(\frac72:\left(\frac85-\frac23\right)\)

\(=\frac72:\left(\frac{24}{15}-\frac{10}{15}\right)\)

\(=\frac72:\frac{14}{15}=\frac72\cdot\frac{15}{14}=\frac{15}{2\cdot2}=\frac{15}{4}\)

=3/5*\((\)2/7+4/7\()\)+2/5

=3/5*6/7+2/5

=18/35+2/5

=32/35

Giải chi tiết tiết hộ mình nhé

Giúp 

c1 :(5/4 + 2/5) : 5/6 = 33/20 : 5/6 = 99/50 

c2 :(5/4 + 2/5) : 5/6 = 5/4 : 5/6 + 2/5 : 5/6 =99/50

c1 : 3/4 x 2/5 - 3/4 x 2/7 = 3/4 x (2/5 - 2/7) = 3/4 x 4/35 = 3/35

c2 : 3/4 x 2/5 - 3/4 x 2/7 = 3/35

c1 : 2/3 : (5/6 x 9/10) = 2/3 : 3/4 = 8/9

c2 : 2/3 : (5/6 x 9/10) = 5/6 : 2/3 x 9/10 : 2/3 = 27/16 * cái này chx chắc:"> quên mất cách lm;-;"" "

Tham khảo nhé bạn :))

bbbbb