ban giai ho minh

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: =17/21(3/5+2/5)=17/21

ko ai bit thi thui ko tra loi thi cam

3/22 x 33/11 x 22= 3/22 x22 x 3=3 x 3=9

3/5 x 17/21 + 17/21 + 2/5= 17/21(3/5 + 2/5)= 17/21x 1=17/21

(1/2+1/3)2/5=1/2x2/5+1/3x2/5 =1/5+2/15=1/3

Bài 1 : Tính bằng cách thuận tiện 

A = 3/13 x 5/7 + 2/13 x 3/7

= 2/13 + 1/13 x 5/7 + 2/13 x 3/7

=  2/13 x 72/91 + 2/13 x 3/7

= 2/13 x ( 72/91 + 3/7 )

= 2/13 x  37/24

= 37/156.

B = 21/22 x 17/8 + 21/8 x 7/22

= 21/22 x 17/8 + 17/8 + 4/8 x 7/22

=  21/22 x 17/8 + 17/8 x 7/44

=  ( 21/22 + 7/44 ) x 21/22

=  31/44 x 21/22

=  651/968.

Chúc bạn học tốt!!!

a: \(=\dfrac{3}{5}:\dfrac{7}{5}=\dfrac{3}{5}\cdot\dfrac{5}{7}=\dfrac{3}{7}\)

b: \(=\dfrac{9}{17}\left(\dfrac{8}{5}-\dfrac{3}{5}\right)+\dfrac{8}{17}\)

=9/17+8/17=1

c: =>x-3/10=7/15*1/5=7/75

=>x=7/75+3/10=59/150

a c1 (1/2+1/3)x2/5

=5/6x2/5

=1/3

c2 1/2 x2/5+1/3x2/5

=1/5+2/15

=1/3

a) Cách 1 :

 \(\left(\frac{1}{2}+\frac{1}{3}\right)\times\frac{2}{5}\)

= \(\left(\frac{3}{6}+\frac{2}{6}\right)\times\frac{2}{5}\)

= \(\frac{5}{6}\times\frac{2}{5}\)

= \(\frac{10}{30}=\frac{1}{3}\)

Cách 2 :

 \(\left(\frac{1}{2}+\frac{1}{3}\right)\times\frac{2}{5}\)

= \(\frac{1}{2}\times\frac{2}{5}+\frac{1}{3}\times\frac{2}{5}\)

= \(\frac{2}{10}+\frac{2}{15}\)

= \(\frac{10}{30}=\frac{1}{3}\)

b) Cách 1 :

\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}\)

= \(\frac{51}{105}+\frac{34}{105}\)

= \(\frac{85}{105}=\frac{17}{21}\)

Cách 2 : 

\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}\)

= \(\left(\frac{3}{5}+\frac{2}{5}\right)\times\frac{17}{21}\)

= \(1\times\frac{17}{21}\)

= \(\frac{17}{21}\)

Nếu đúng thì mọi người t i c k em nhé:3 

1a) \(\frac{10}{11}:\frac{11}{3}=\frac{10}{11}.\frac{3}{11}=\frac{30}{121}\)

b) \(3,42:0,75.8,4-6,8\)

\(=4,56.8,4-6,8=38,304-6,8=31,504\)

2a) \(\frac{21}{11}.\frac{22}{17}.\frac{68}{63}=\frac{21.22.68}{11.17.63}=\frac{7.3.2.11.17.4}{11.17.3.3.7}=\frac{2.4}{3}=\frac{8}{3}\)

b) \(\frac{5}{14}.\frac{7}{13}.\frac{26}{25}=\frac{5.7.26}{14.13.25}=\frac{5.7.13.2}{2.7.13.5.5}=\frac{1}{5}\)

\(\frac{10}{11}:1\frac{1}{3}\)

\(=\frac{10}{11}:\frac{4}{3}\)

\(=\frac{10}{11}\cdot\frac{3}{4}\)

\(=\frac{15}{22}\)

\(3,42:0,57\cdot8,4-6,8\)

\(=6\cdot8,4-6,8\)

\(=50,4-6,8\)

\(43,6\)

2.

\(\frac{21}{11}\cdot\frac{22}{17}\cdot\frac{68}{63}\)

\(=\frac{21\cdot22\cdot68}{11\cdot17\cdot63}\)

\(=\frac{21\cdot11\cdot2\cdot17\cdot4}{11\cdot17\cdot21\cdot3}\)

\(=\frac{̸21\cdot̸11\cdot2\cdot̸17\cdot4}{̸11\cdot̸17\cdot̸21\cdot3}\)

\(=\frac{8}{3}\)

\(\frac{5}{14}\cdot\frac{7}{13}\cdot\frac{26}{25}\)

\(=\frac{5\cdot7\cdot26}{14\cdot13\cdot25}\)

\(=\frac{̸5\cdot̸7\cdot̸13\cdot2}{̸7\cdot2\cdot̸13\cdot̸5\cdot5}\)

\(=\frac{2}{10}\)

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

c1 = 5/6 x 2/5 = 1/3

c2 = 1/2 x 2/5 + 1/3 x 2/5

= 1/5 + 2/15 

= 1/3

3/5 x 17/21 x 2/5

c1 := 17/35 x 2/5 = 34/175

c2 : = (3/5 x 2/5) x 17/21 

= 6/25 x 17/21 

= 34/175?

( 1/3 - 1/5 ) x 1/2

c1 : = 2/15 x 1/2 

= 1/15

c2 : = 1/3 x 1/2 - 1/5 x 1/2

= 1/6 - 1/10

= 1/15