a) `123 - 27 + 27 + 13 - 123`

`= (123 - 123) + (27 - 27) + 13`

`= 0 + 0 + 13`

`= 13`

`---`

b) `175 + 25 + 13 + 15 - 175 - 25`

`= (175-175)+(25-25)+25+13`

`=0+0+25+13`

`=28`

`---`

c) \(53\times39+47\times39+53\times21+47\times21\)

\(=\text{[}\left(53+47\right)\times39]+\left[\left(53+47\right)\times21\right]\)

\(=\left(100\times39\right)+\left(100\times21\right)\)

\(=3900+2100\)

`=6000`

`---`

d) \(49\times35+49\times16-49\times61\)

`=` \(49\times\left(35+16-61\right)\)

`=` \(49\times\left(-10\right)\)

`=-490`

21.35-3.25.7

= 21.35-21.25

= 21.(35-25)

= 21. 10

=210

77 - 11.( 30+7)

= 11.7 -11.30 -11.7

= 11.7-11.7 -11.30

= -11.30

= -330

21.35-3.25.7=210

77-11(30+7)=-330

85(35-27)-35(85-27)=-1350

47(45-15)-47(45+15)=-2820

a)21.35-3.25.7

=21.35-(3.7).25

=21.35-21.25

=21.(35-25)

=21.10=210

a, 85.(35-27)-35.(85-27)

=85.35-85.27-35.85+35.27

=85.27+35.27

=27.(85+35)

=27.120=3240

b, 47.(45-15)-47.(45+15)

=47.30-47.60

=47.(30-60)

=-1410

a)85.(35-27)-35.(85-27)

=85.35-27-35.85-27

=(85-85).(35-35).(27-27)

=0.0.0

=0

b)47.(45-15)-47.(45+15)

=47.45-15-47.45+15

=(47-47).(45-45).(15+15)

=0.0.30

=0

a) - 1350

b) - 141o

a) 85 . ( 35 - 27 ) - 35 . ( 85 - 27 )

= 85 . 35 - 85 . 27 - 35 . 85 + 35 . 27

= ( 85 . 35 - 35 . 85 ) - 27 . ( 85 - 35 )

= 0 - 27 . 50

= 0 - 1350

= -1350

b) 47 . ( 45 - 15 ) - 47 . ( 45 + 15 )

= 47 . ( 45 - 15 - 45 - 15 )

= 47 . (-30)

= -1410

Học tốt !!!

=))

a, 21.35-3.25.7=21.35-21.25=21.(35-25)=21.10=210

b, 77-11.(30+7)=77-330-77=-330

c, 85.(35-27)-35.(85-27)=85.35-85.27-35.85+35.27=0

d, 47.(45-15)-47.(45+15)=47.45-47.15-47.45-47.15=-2(47.15)=1410

a, 21.35-3.25.7=21.35-21.25=21.10=210

b,77-11.(30+7)=77-11.30-11.7=-11.30=-330

c,85.(35-27)-35.(85-27)=85.35-85.27-85.35+35.27=27.(-50)=-1350

d, 47.(45-15)-47.(45+15)=47.45-47.15-47.45-47.15=-47.30=-1410

a, 21 . 35 - 3 . 25 . 7

= (21 . 35) - (3 . 25 . 7)

= 735 - 525

= 210

b, 77-11.(30+7)

= 77 - 11.30 - 11.7

= -11.30

= -330

c, 85.(35-27)-35.(85-27)

= 85.35 - 85.27 - 85.35 + 35.27

= 27.(-50)

= -1350

d, 47.(45-15)-47.(45+15)

= 47.45 - 47.15 - 47.45 - 47.15

= -47.30

= -1410

a,
       85.(35-27)-35.(85-27)
     =85.35-85.27-35.85-35.27
     =85.35-35.85-85.27.35.27
     =85.27-35.27
     =(85-35).27
     =100.27/2
     =2700/2
     =1350

Bài 1:tính 

a)65.(-19)+19.(-35)

=65.(-19)+(-19).35

=(-19).(65+35)

=(-19).100

=-1900

b)85.(35-27)-35.(85-27)

=85.35-85.27-35.85+35.27

=(85.35-35.85)+(-85.27+35.27)

=27.(-85+35)

=27.(-50)

=1350

c)47.(45-15)-47.(45+15)

=47.[(45-15)-(45+15)]

=47.[30-60]

=47.(-30)

=-1410

Bài2: Tìm các số nguyên x biết

a)(-2).(x+6)+6.(x-10)=8

-2x-12+6x-60=8

4x-72=8

4x=72+8

4x=50

 x=\(\frac{25}{2}\)

b)(-4).(2x+9)-(-8x+3)-(x+13)=0

-6x-36+8x-3-x-13=0

x-41=0

     x=41

Bài 1: Tính

a) \(65.\left(-19\right)+19.\left(-35\right)\)

= \(-1235+-665\)

= \(-1900\)

b) \(85.\left(35-27\right)-35.\left(85-27\right)\)

= \(-1350\)

c) \(47.\left(45-15\right)-47.\left(45+15\right)\)

=\(-1410\)

Bài 2: Tìm x:

\(\left(-2\right).\left(x+6\right)+6.\left(x-10\right)=8\)

\(x=20\)

Cảm ơn các bạn nha

dễ mà bạn, dựa vào kiến thức dẫ học kết hợp với việc bạn làm nháp và dùng máy tính để hỗ trợ thì chắc chắc những bài trên chỉ là chuyện nhỏ

haidangbb làm ra lun đi

-300

-1350

-1410

a,21*35-3*25*7

=21*35-21*25

=21*(35-25)

=21*10

=210

b,77-11*(30+7)

=77-11*30-11*7

=11*30=330

c,

a) 21 . 35 - 3.25.7

= 21 . 35 - ( 3.7 ) . 25

= 21 . 35 - 21.25

= 21 . ( 35 - 25 )

= 21 . 10

=210

b) 77 - 11 . ( 30+7 )

= 77 -(11 . 30 + 11 . 7)

= 77 - 330 - 77

= 77 - 77 - 330

= 0 - 330

= 330

c) 85 . ( 35-27) - 35 ( 85 - 27 )

= 85 . 8 - 35 . 58

= 35 . 8 + 50 .8 - 35 . 58

= ( 35 . 8 - 35 . 58 ) + 50.8

= 35 . (-50) + 50 .8

= -35 . 50 + 50 . 8

= 50 ( -35 + 8 )

= 50 . (-27)

=-1350

d)47 . ( 45 - 15 ) - 47 . ( 45+15 )

= 47 . 30 - 47.60

= 47 ( 30 - 60 )

= 47 . (-30 )

=-1410