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

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

chúc bạn học tốt

giúp mình với

\(a,\dfrac{7}{9}-\dfrac{2}{7}+\dfrac{2}{3}+\dfrac{4}{7}\\ =\left(\dfrac{7}{9}+\dfrac{6}{9}\right)+\left(\dfrac{4}{7}-\dfrac{2}{7}\right)\\ =\dfrac{13}{9}+\dfrac{2}{7}\\ =\dfrac{109}{63}\\ b,13,8+7-5,25+4,25\\ =\left(13,8+7\right)-\left(5,25-4,25\right)\\ =20,8-1\\ =19,8\)

a \(\left(\dfrac{4}{7}-\dfrac{2}{7}\right)+\left(\dfrac{7}{9}+\dfrac{2}{3}\right)=\dfrac{2}{7}+\left(\dfrac{7}{9}+\dfrac{6}{9}\right)=\dfrac{2}{7}+\dfrac{15}{9}=\dfrac{2}{7}+\dfrac{5}{3}=\dfrac{6}{21}+\dfrac{35}{21}=\dfrac{41}{21}\)

b \(20.8-1=19.8\)

a. (4578+5422) + (7895+2105)

= 1000              +      1000

= 2000

b. (3012+6988) + (5422+4538)

=      10000       +    1000

= 2000

Học tốt nhé

a, 4578 + 7895 + 5422 + 2105 

 = ( 4578 + 54 22 ) + ( 7895 +2105 )

= 10 000 + 10 000

= 20 000 

b, 5462 + 3012 + 6988 + 4538 

= ( 5462 + 4538 ) + ( 3012 + 6988 )

= 10 000 + 10 000

= 20 000

a) 4578 + 7895 + 5422 + 2105

= ( 4578 + 5422 ) + ( 7895 + 2105 )

= 10000 + 10000

= 20000

b) 5462 + 3012 + 6988 + 4538

= ( 5462 + 4538 ) + ( 3012 + 6988 )

= 10000 +10000

= 20000

     566 x 23 + 466 x 23 + 23 

   = ( 566 + 466 + 1 ) x 23

   =            1033 x 23

   =        ( 1000 x 23) + (30 x 23) + (3 x 23)

   =              23000 +  690 + 69 =     23759

         lưu ý: 23:23=1    

 566x23+433x23+23

=566x23+433x23+1x23

=(566 +433 + 23)x23

=1000 x 23

=23000

Lộn (566+433+1) nha

= 6,48 x ( 1125- 112-13)
= 6,48 x 1000
= 6480

6,48 x 1125 - 6,48 x 112 - 6,48 x 13
= 6,48 x ( 1125 + 112 + 13 )
= 6,48 x 1250
= 8100
( k cho mik nhé)

b, 0,04 x 47 x 25 

= (0,04 x 25) x 47

= 1 x 47

= 47

c, 4x 6,9 x 2,5

= 4 x 2,5 x 6,9

= 10 x 6,9

= 69 

a) 4.6,9.2,5

  =̣(4.2,5).6,9

 =10.6,9

 =69

b)0,04.47.25

 =(0,04.25).47

 =1.47

 =47

a) 21,63 + 35,26 + 8,37 = (21,63 + 8,37) + 35,26 = 30 + 35,26 = 65,26.

a/ 25 x 69 x 4

= (25 x 4) x 69

=    100    x 69

=         6900

b/ 38 x 85 + 38 x 15

= 38 x (85 + 15)

= 38 x 100

= 3800

a/ 25 x 69 x 4

= (25 x 4) x 69

=    100    x 69

=         6900

b/ 38 x 85 + 38 x 15

= 38 x (85 + 15)

= 38 x 100

= 3800

 27 x 782 + 72 x 782 + 782

=27 x 782 + 72 x 782 + 782 x 1

=782 x (27 +72 + 1)

=782 x 100

= 78 200