Question

_{Bài 1:}

_{a) 2/5 x 25/29 + 3/5 x 25/29                b)5/2x3/7 - 3/14 : 6/7}

_{c)15/4 : 5/12 - 6/5 : 11/15}

_{Bài 2:}

_{a)2/3 x 20/21 x 3/2 x 7/5                       b)5/17x21/32x47/24x0}

_{c)11/3x26/7 -26/7 x 8/3}

Answer 1

bài 1 :

a) 2/5 x 25/29 + 3/5 x 25/29

= (2/5 + 3/5) x 25/29

= 1 x 25/29

= 25/29

b) 5/2 x 3/7 - 3/14 : 6/7

= 15/14 - 1/4

= 23/28

c) 15/4 : 5/12 - 6/5 :11/15

= 9 - 18/11

= 81/11

 

Answer 2

`2/5 xx 25/29 + 3/5 xx 25/29`

` = 25/29 xx ( 2/5 + 3/5)`

`=25/29 xxx 5/5`

`= 25/29 xx1`

`= 25/29`

__________________________

`5/2 xx 3/7 - 3/14 : 6/7`

` = 5/2 xx 3/7 - 3/14 xx 7/6`

` = (5xx3)/(2xx7) - (3xx7)/(14xx6)`

` = 15/14 - 1/4`

`= 23/28`

________________________

`15/4 : 5/12 - 6/5 : 11/15`

`= 15/4 xx 12/5 - 6/5 xx 15/11`

` = (15xx12)/(4xx5) - ( 6xx15)/(5xx11)`

`=9 - 18/11`

` = 99/11 - 18/11`

`= 81/11`

______________________________

`2/3 xx 20/21 xx 3/2 xx 7/5`

` = (2xx20xx3xx7)/(3xx21xx2xx5)`

` = 840/630`

`= 4/3`

____________________________

`5/17 xx 21/32 xx 47/24 xx 0`

` = 0`

___________________________

`11/3 xx 26/7 - 26/7 xx 8/3`

` = ( 11/3 - 8/3) xx 26/7`

`= 3/3 xx 26/7`

`= 1 xx 26/7`

`= 26/7`

Answer 3

bài 2 :

a) 2/3 x 20/21 x 3/2 x 7/5

= 40/63 x 3/2 x 7/5

= 20/21 x 7/5

= 4/3

b) 5/17 x 21/32 x 47/24 x 0 

= (5/17 x 21/32 x 47/24) x 0

= 0

c) 11/3 x 26/7 - 267 x 8/3

= (11/3 - 8/3) x 26/7

= 1 x 26/7 

= 26/7

Answer 4

\(1.a\)\(\dfrac{2}{5}\times\dfrac{25}{29}+\dfrac{3}{5}\times\dfrac{29}{25}\)

\(=\dfrac{25}{29}+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=\dfrac{25}{29}+\dfrac{1}{1}\)

\(\dfrac{25}{29}+\dfrac{29}{29}=\dfrac{54}{29}\)

\(b.\dfrac{5}{2}\times\dfrac{3}{7}-\dfrac{3}{14}:\dfrac{6}{7}\)

\(=\dfrac{15}{14}-\dfrac{21}{84}=\dfrac{30}{84}-\dfrac{21}{84}=\dfrac{9}{84}\)

\(c.\dfrac{15}{4}:\dfrac{5}{12}-\dfrac{6}{5}:\dfrac{11}{15}\)

\(=\dfrac{180}{48}-\dfrac{90}{55}=\dfrac{9900}{2640}-\dfrac{4320}{2640}=\dfrac{5580}{2640}=\dfrac{279}{132}=\dfrac{93}{44}\)

\(2.a.\dfrac{2}{3}\times\dfrac{20}{21}\times\dfrac{3}{2}\times\dfrac{7}{5}\)

\(\dfrac{40}{63}\times\dfrac{3}{2}\times\dfrac{7}{5}=\dfrac{120}{126}\times\dfrac{7}{5}=\dfrac{840}{630}=\dfrac{28}{21}\)

\(b.\dfrac{5}{17}\times\dfrac{21}{32}\times\dfrac{47}{24}\times0\)

\(=\dfrac{105}{544}\times\dfrac{47}{24}\times0=\dfrac{4935}{13056}\times0=0\)

\(c.\dfrac{11}{3}\times\dfrac{26}{7}-\dfrac{26}{7}\times\dfrac{8}{3}\)

\(=\dfrac{26}{7}\times\left(\dfrac{11}{3}-\dfrac{8}{3}\right)=\dfrac{26}{7}\times\dfrac{3}{3}=\dfrac{78}{21}=\dfrac{26}{7}\)