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

\(=\left(\dfrac{7}{5}+\dfrac{4}{3}\right)\cdot2=\dfrac{21+20}{15}\cdot2=\dfrac{82}{15}\)

82/15

C!:7/5 + 4/3 + 7/5 + 4/3

=31/15+31/15

=62/15

C2:7/5 + 4/3 + 7/5 + 4/3

=7/5+4/3

=62/15

C!:7/5 + 4/3 + 7/5 + 4/3

=31/15+31/15

=62/15

C2:7/5 + 4/3 + 7/5 + 4/3

=7/5+4/3

=62/15

C!:7/5 + 4/3 + 7/5 + 4/3

=31/15+31/15

=62/15

C2:7/5 + 4/3 + 7/5 + 4/3

=7/5+4/3

=62/15

Cách 1:

     \(\dfrac{3}{7}\) x \(\dfrac{16}{33}\) + \(\dfrac{16}{33}\) x \(\dfrac{4}{7}\)

=    \(\dfrac{48}{231}\) + \(\dfrac{64}{231}\)

= \(\dfrac{112}{231}\)

= \(\dfrac{16}{33}\)

cách 2:  \(\dfrac{3}{7}\) x \(\dfrac{16}{33}\) + \(\dfrac{16}{33}\) x \(\dfrac{4}{7}\)

       = \(\dfrac{16}{33}\) x ( \(\dfrac{3}{7}\) + \(\dfrac{4}{7}\))

      = \(\dfrac{16}{33}\) x \(\dfrac{7}{7}\)

     = \(\dfrac{16}{33}\)

9,3×6,7+3,3

\(\dfrac{4}{7}:\dfrac{4}{3}+5:\dfrac{4}{3}=\left(\dfrac{4}{7}+5\right):\dfrac{4}{3}=\dfrac{39}{7}:\dfrac{4}{3}=\dfrac{39}{7}\times\dfrac{3}{4}=\dfrac{117}{28}\)

\(\dfrac{4}{7}:\dfrac{4}{3}+5:\dfrac{4}{3}=\dfrac{3}{7}+\dfrac{15}{4}=\dfrac{12}{28}+\dfrac{105}{28}=\dfrac{117}{28}\)

\(\dfrac{3}{4}\times\dfrac{2}{5}-\dfrac{3}{4}\times\dfrac{2}{7}=\dfrac{3}{4}\times\left(\dfrac{2}{5}-\dfrac{2}{7}\right)=\dfrac{3}{4}\times\dfrac{4}{35}=\dfrac{12}{140}=\dfrac{3}{35}\)

\(\dfrac{3}{4}\times\dfrac{2}{5}-\dfrac{3}{4}\times\dfrac{2}{7}=\dfrac{3}{10}-\dfrac{3}{14}=\dfrac{42}{140}-\dfrac{30}{140}=\dfrac{12}{140}=\dfrac{3}{35}\)

\(\left(\dfrac{2}{3}-\dfrac{4}{7}\right)\times\dfrac{2}{5}=\dfrac{2}{21}\times\dfrac{2}{5}=\dfrac{4}{105}\)

\(\left(\dfrac{2}{3}-\dfrac{4}{7}\right)\times\dfrac{2}{5}=\dfrac{2}{3}\times\dfrac{2}{5}-\dfrac{4}{7}\times\dfrac{2}{5}=\dfrac{4}{15}-\dfrac{8}{35}=\dfrac{140}{525}-\dfrac{120}{525}=\dfrac{20}{525}=\dfrac{4}{105}\)

#YVA

4/7:4/3+5:4/3

= 3/7 + 15/4

=4 5/28

4/7:4/3+5:4/3

= (4/7+5) x 3/4

=4 5/28

3/4x2/5-3/4x2/7

=3/10 - 3/14

=3/35

3/4x2/5-3/4x2/7

=3/4x(2/5-2/7)

=3/35

(2/3-4/7)x2/5

=2/21x2/5

=4/105

(2/3-4/7)x2/5

=2/3x2/5-4/7x2/5

=4/105

c1

(6/11+5/11)x3/7

=1x3/7

=3/7

c2

6/11 x 3/7+ 5/11 x 3/7

=18/77+15/77

=33/77 rut gon voi 11 = 3/7

Mik có sửa lại đề

C1: \(\dfrac{6}{7}\times\dfrac{1}{2}+\dfrac{6}{7}\times\dfrac{1}{4}=\dfrac{3}{7}+\dfrac{3}{14}=\dfrac{6}{14}+\dfrac{3}{14}=\dfrac{9}{14}\)

C2:\(\dfrac{6}{7}\times\dfrac{1}{2}+\dfrac{6}{7}\times\dfrac{1}{4}=\dfrac{6}{7}\times\left(\dfrac{1}{2}+\dfrac{1}{4}\right)=\dfrac{6}{7}\times\left(\dfrac{2}{4}+\dfrac{1}{4}\right)=\dfrac{6}{7}\times\dfrac{3}{4}=\dfrac{9}{14}\)

1) C1: 8^5 : 8^4 = 32768 : 4096 = 8

   C2: 8^5 : 8^4 = 8^ 5-4 = 8^1 = 8

2) C1: 7^4 : 7^4 = 2401 : 2401 = 1

   C2: 7^4 : 7^4 = 7^4-4 = 7^0 = 1

              cho mk nha.