1. 125-125+39+11
=50
2. 39.46+30.(-61)-39.76
=1794 + (-1830) -2964
= -3000
3. -195.56-43.195-195
= -10920 - 8385 - 195
= -19500
mk lm nửa thôi nhé bn vì bh mik có vc bận r

 

a) A=(135-35).(-47)+53.(-48-52)

      = 100.(-47) + 53.(-100)

     = 100.(-47) + (-53).100

    = 100.(-47+-53)

    = 100.(-100)

   = -10000

làm thử đi đi 

b) B= 25.(75-49) + 75.l25-49l

      = 25.26 + 75.24

     = 50.( 13 + 36)

     = 50.49

     = 2450

a. \(678\times\left(276+49\right)-678\times\left(149+76\right)\)

\(=678\times\left[\left(276+49\right)-\left(149+76\right)\right]\)

\(=678\times\left(276+49-149-76\right)\)

\(=678\times\left(200-100\right)\)

\(=67800\)

b. \(23\times157+15\times46-28\times87\)

\(=3611+690-2436\)

\(=1865\)

c. \(12:\left\{390:\left[500-\left(125+35\times7\right)\right]\right\}\)

\(=12:\left\{390:\left[500-\left(125+245\right)\right]\right\}\)

\(=12:\left\{390:\left[500-370\right]\right\}\)

\(=12:\left\{390:130\right\}\)

\(=12:3\)

\(=4\)

\(\dfrac{7}{19}x\dfrac{8}{23}+\dfrac{7}{19}x\dfrac{15}{23}+1\dfrac{7}{19}\)

= \(\dfrac{7}{19}x\left(\dfrac{8}{23}+\dfrac{15}{23}\right)+1+\dfrac{7}{19}\)

=\(\dfrac{7}{19}x1+1+\dfrac{7}{19}\)

= \(\dfrac{7}{19}+1+\dfrac{7}{19}=1\dfrac{14}{19}\) = \(\dfrac{33}{19}\)

\(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{3}{21}-\dfrac{17}{32}\)

=  \(\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{1}{7}-\dfrac{17}{32}\)

= \(\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{49}{32}-\dfrac{17}{32}\right)\)

= 1 + 1 + 1 = 3

\(\dfrac{8}{9}x\dfrac{15}{16}x\dfrac{24}{25}x\dfrac{35}{36}x\dfrac{48}{49}x\dfrac{63}{64}\)

= \(\dfrac{3}{4}\) *Câu này bạn tự sử dụng gạch nhé!

`1,`

`a,`

`7/19 \times 8/23 + 7/19 \times 15/23 + 1 7/19`

`= 7/19 \times 8/23 + 7/19 \times 15/23 + 1 + 7/19`

`= 7/19 \times (8/23 + 15/23 + 1) + 1`

`= 7/19 \times 2 + 1`

`=14/19 + 1`

`= 33/19`

`b,`

`75/100 + 18/21 + 49/32 + 1/4 + 3/21 - 17/32`

`= 75/100 + (18/21 + 3/21) + (49/32 - 17/32) + 1/4`

`= 0,75 + 1 + 1 + 0,25`

`= (0,75 + 0,25) + 1 + 1`

`= 1+1+1=3`

`c,`

`8/9 \times 15/16 \times 24/25 \times 35/36 \times 48/49 \times 63/64`

`=` \(\dfrac{2\times3}{3\times3}\times\dfrac{3\times5}{4\times4}\times\dfrac{3\times4\times2}{5\times5}\times\dfrac{5\times7}{6\times6}\times\dfrac{6\times8}{7\times7}\times\dfrac{7\times9}{8\times8}\)

`= 3/4` (bạn sử dụng gạch, rút gọn các số là được nhé).

45-58+(-45)+(+58)-3=45-58-45+58-3=(45-45)+(58-58)-3=-3

(-57)-(-12)+3-(-57)=-57+12+3+57=(-57+57)+12+3=15

-(-24)-(-30)+(-24)-30+8=24+30-24-30+8=(24-24)+(30-30)+8=8

-(-12)+(+19)-(+12)+8-19=12+19-12+8-19=(12-12)+(19-19)+8=8

47-(-53)+(-47)-(+53)=47+53-47-53=(47-47)+(53-53)=0

-(+28)+32-(-28)+(-34)=-28+32+28-34=(-28+28)-(34-32)=-2

15-(+72)+(-15)+(+72)=15-72-15+72=(15-15)+(72-72)=0

20-(+46)+(-25)-(-46)=20-46-25+46=(20-25)+(46-46)=-5

28-(-32)+(-28)-32+5=28+32-28-32+5=(28-28)+(32-32)+5=5

-75+(-49)+(+75)+49-12=-75-49+75+49-12=(-75+75)+(49-49)-12=-12

\(...=45-58-45+58-3=-3\)

\(...=-57+12+3+57=15\)

\(...=24+30-24-30+8=8\)

\(...=12+19-12+8-19=8\)

\(...=47+53-47-53=0\)

\(...=-28+32+28-34=-2\)

\(...=15-72-15+72=0\)

\(...=20-46-25+46=-5\)

\(=...28+32-28-32+5=5\)

\(...=-75-49+75+49-12=-12\)

    -5 + (-37 - 45 + 51) - (-37 + 51)

=  -5  - 37 - 45 + 51 + 37 - 51

=  - (5 + 45) - (37 - 37) + (51 - 51)

= - 50 - 0 + 0

= - 50

  - (15 - 47 + 58) + (15 - 47 ) + 3

= - 15 + 47 - 58 + 15 - 47 + 3

= (-15 + 15) + (47 - 47) - (58 - 3)

= 0 + 0 - 55

= - 55

  (53 - 45 - 49) - (53 + 45 - 49)

= 53 -  45 - 49 - 53 - 45 + 49

= (53 - 53) + (-49 + 49) - (45 + 45)

= 0 + 0 - 90

= - 90 

    13 - 15 + 49 - 13 + 15 - 48

=  (13 - 13) + (-15 + 15) + (49 - 48)

= 0 + 0 + 1

=  1 

15+13 -15-13 +49-48

   254 - 49 - 75 + 254 - 175 + 549

= ( 549 - 49 ) - ( 175 + 75 ) + 254 + 254

= 500 - 250 + 254 + 254

= 758

1) 2155 - (174 + 2155) + (-68 + 174)

= 2155 - 174 - 2155 - 68 + 174

= (2155 - 2155) + (-174 + 174) - 68

= 0 + 0 - 68

= -68

2) -25 . 72 + 25 . 21 - 49 . 25

= 25 . (-72) + 25 . 21 - 49 . 25

= 25 . (-72 + 21 - 25)

= 25 . (-76)

= -1900

3) 35 . (14 - 23) - 23 . (14 - 35)

= 35 . 14 - 35 . 23 - 23 . 14 + 23 . 35

= (35 . 14 - 23 . 14) + (-35 . 23 + 23 . 35)

= [14 . (35 - 23)] + 0

= 14 . 12

= 168

4) 8154 - (674 + 8154) + (-98 + 674)

= 8154 - 674 - 8154 - 98 + 674

= (8154 - 8154) + (-674 + 674) - 98

= 0 + 0 - 98

= -98

5) -25 . 21 + 25 . 72 + 49 . 25

= 25 . (-21) + 25 . 72 + 49 . 25

= 25 . (-21 + 72 + 49)

= 25 . 100

= 2500

6) 27 . (13 - 16) - 16 . (13 - 17)

= 27 . 13 - 27 . 16 - 16 . 13 + 16 . 17

= (27 . 13 - 16 . 13) + (-27 . 16 + 16 . 17)

= [13 . (27 - 16)] + [16 . (-27 + 17)]

= (13 . 11) + [16 . (-10)]

= 143 - 160

= -17

1) 2155-2155-(174-174)+-68=0+0+-68=-68

giờ mk ghi kq được ko