a) 19,17x25x4=19,17(25x4)=19,17x100=1917

b)1,79x(8x125)=1,79x1000=1790

chúc bạn học tốt

a, 5 x 4 x 2 x 25

= (5 x 2) x (4 x 25)

= 10 x 100

= 1 000

\(5\times4\times2\times25\)

\(=\left(4\times25\right)\times\left(5\times2\right)\)

\(=100\times10\)

\(=1000\)

a,5 x 4 x 2 x 25                                                                                           = (5 x 2) x ( 4 x 25)                                                                                    =   10    x     100                                                                                                 1 000

a. 3100 : (5 x 2)

= 3100 : 10

= 310

b.  4 x 21 x 25

= ( 4 x 25) x 21

= 100 x 21

= 2100

=(25x4)x165=165x100=16500

25 x 165 x 4

= 25 x 660

=16500

Ta có: 25 x 165 x 4 = ( 25 x 4 ) x 165 = 100 x 165 = 16500

4 x 18 x 25

= 18 x (4 x 25)

= 10 x 100 = 1800

(25 x 4 ) x (35 x 6 ) = 100 x 210 = 21000

25 x 35 x 4 x 6 

= (25 x 4 ) x ( 35 x 6 ) 

= 100 x 210

= 21 000 

25x35x4x6

=(25x4) x (35x6)

=100x210

=21000

\(25\times35\times4\times6\)

\(=\left(25\times4\right)\times\left(35\times6\right)\)

\(=100\times210\)

\(=21000\)

\(25\times35\times4\times6\)

\(=\left(25\times4\right)\times\left(35\times6\right)\)

\(=100\times210\)

\(=21000\)

\(~HT~\)

=25 x 4 x (35 x 6)

=100 x 210

=21000

`(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`