a) 15 / 17 x 4 / 7 + 15 / 17 x 3 / 7

= 15 / 17 x (4 / 7 + 3 / 7)

=15 / 17 x 1=15 / 17 

b) 29 / 12 : 1 / 2 - 5 / 12 :1 / 2 

=29 / 12  x2 - 5 / 12 x 2 

=(29 / 12 - 5 / 12)x2

=2x2=4

a) 15 / 17 x 4 / 7 + 15 / 17 x 3 / 7

= 15 / 17 x (4 / 7 + 3 / 7)

=15 / 17 x 1=15 / 17 

b) 29 / 12 : 1 / 2 - 5 / 12 :1 / 2 

=29 / 12  x2 - 5 / 12 x 2 

=(29 / 12 - 5 / 12)x2

=2x2=4

chúc bạn học tốt !

=15/17 x (4/7 + 3/7) - 1/3
=15/17 x 1 - 1/3
=15/17 x (3/3 - 1/3)
=15/17 x 2/3
=30/51

= \(\dfrac{4}{15}\) x ( 3 + 2 - 5 )

=  \(\dfrac{4}{15}\) x 0

= 0

( 3+2-5) x 4/15

=  0        x 4/15

=  0

( 3+2-5) x \(\dfrac{4}{15}\)

=  0  x \(\dfrac{4}{15}\)

=0

`(2/3xx4/5)xx5/6`

`=2/3xx4/5xx5/6`

`=2/3xx4/6`

`=2/3xx2/3`

`=1`

__

`(4/5+5/4)xx3/4`

`=(16/20+25/20)xx3/4`

`=41/20xx3/4`

`=123/80`

__

`27/12+17/6-25/36-15/6`

`=(27/12-25/36)+(17/6-15/6)`

`=(81/36-25/36)+2/6`

`=56/36+2/6`

`=56/36+12/36`

`=68/36`

`=17/9`

\(\dfrac{3}{12}\)x\(\dfrac{15}{6}\)x\(\dfrac{8}{5}\)

=> \(\dfrac{5}{8}\)x\(\dfrac{8}{5}\)

=>1

\(\dfrac{3}{12}\times\dfrac{15}{6}\times\dfrac{8}{5}=1\)

=1

215(12 + 38) = 215.50 = 10750

3450(15 - 5) = 3450.10 = 34500

215(12 + 38) = 215.50 = 10750

3450(15 - 5) = 3450.10 = 34500

\(a.60\times\left(\frac{7}{12}+\frac{4}{15}\right)\)

\(=60\times\left(\frac{35}{60}+\frac{16}{60}\right)\)

\(=60\times\frac{51}{60}\)

\(=51\)

\(b.\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\times\frac{5}{6}\times\frac{6}{7}\times\frac{7}{8}\times\frac{8}{9}\)

\(=\frac{1\times2\times3\times4\times5\times6\times7\times8}{2\times3\times4\times5\times6\times7\times8\times9}\)

\(=\frac{1}{9}\)

1/125 nha em 

HT  

@@@@@@ 

@@@@@@@@@@@@@@@

1/25 nha

HT

1/125

a: 3km75m=3,075m

\(\dfrac{1}{4}m^2=25dm^2\)

3h15'=195p

b: 26320:35=752

c: =3/5(5/12+7/12)

=3/5

a, \(3km75m=3075m\)

\(\dfrac{1}{4}m^2=25\text{d}m^2\)

`3` giờ `15` phút = `195` phút

b,

`->26320 : 35=752.`

c, \(\dfrac{9}{15}\times\dfrac{5}{12}+\dfrac{9}{15}\times\dfrac{7}{12}=\dfrac{9}{15}\times\left(\dfrac{5}{12}+\dfrac{7}{12}\right)=\dfrac{9}{15}\times1=\dfrac{9}{15}\)

`@mt`