\(a,x-36:18=12-15\\ \Rightarrow x-2=-3\\ \Rightarrow x=-1\\ b,92-\left(17+x\right)=72\\ \Rightarrow17+x=20\\ \Rightarrow x=3\\ c,720:\left[41-\left(2x+5\right)\right]=40\\ \Rightarrow41-\left(2x+5\right)=18\\ \Rightarrow2x+5=23\\ \Rightarrow2x=18\\ \Rightarrow x=9\\ d,\left(x+2\right)^3-23=41\\ \Rightarrow\left(x+2\right)^3=64\\ \Rightarrow\left(x+2\right)^3=4^3\\ \Rightarrow x+2=4\\ \Rightarrow x=2\)

b: =>x+17=20

hay x=3

d: =>x+2=4

hay x=2

A = 1
B = 3
C = 9
D = 2

a) 58.57+58.150-58.125   

=58.(57+150-125)

=58.    82

=    4756        

b)3².5-2².7+83.2019⁰

=9.5-4.7+83

=45-28+83

=100

c)2019+(-247)+(-53)-2019 

 =(2019-2019)+[ (-247)+(-53)]

0+(-300)

= -300             

d)13.70-50 [(19-3²):2+2³]

=13.70-50[10:2+8]

=13.70-50.13

=13.(70-50)

=13.20

=260

2.

a)x-36:18=12-5   

    x-36:18=6

    x-36=6.18   

     x-36=108

      x=108+36

      x=    144                    

b)92-(17+x)=72

17+x=92-72

17+x=20

x=20-17

x=3

c)720:[41-(2x+5)]=40     

41-(2x+5)=720:40

41-(2x+5)=  18

2x+5=41-18

2x+5=23

2x=23-5

2x=18

x=18:2

x=9                 

d) (x+2)³ -23=41

 (x+2)³ =41+23

 (x+2)³ =64

=> (x+2)³ =4³

=>x+2=4

=>x=4-2

=>x=2

a ) x = − 91 60 . b ) x = − 8 9 . c ) x = 35 19 . d ) x = 3 7 .

3/5

1 1/6 

a 4/5 - X = 3/15

X = 4/5 - 3/15

X = 3/5

b X : 2/3 = 1/2

X = 1/2 x 2/3

X = 11/6 

3/5

11/6

Cau 1)

21+(x+23)=50

X+23=50-21

X=29-23

X=6

Cau 2)

125+(x-100)=150

X-100=150-125

X=25+100

X=125

Cau 3)

24+(10-x)=26

10-x=26-24

X=10-2

X=8

câu 1 bỏ dấu ngoặc rồi tính

( 36 + 79 ) + ( 145 _ 79 _ 36 )

\(=36+79+145-79-36\)

\(=\left(36-36\right)+\left(79-79\right)+145\)\

\(=0+0+145=145\)

10 _ [ 12 _ ( -9 _ 1 ) ]

\(=10-12-10\)

\(=10-10-12\)

\(=0-12=-12\)

( 38 _ 29 + 43) _ ( 43 + 38 )

\(=38-29+43-43-38\)

\(=\left(38-38\right)+\left(43-43\right)-29\)

\(=0+0-29=-29\)

271 _ [ ( -43 ) + 271 _ ( -17 ) ]

\(=271+43-271-17\)

\(=\left(271-271\right)+\left(43-17\right)\)

\(=0+26=26\)

- 144 _ [ 29 _ ( + 144 ) _ ( + 144 )]

\(=-144-19+144+144\)

\(=\left(-144+144+144\right)-19\)

\(=144-19=125\)

đợi mk lm tiếp câu 2 nha .

bài 2 tính tổng các số nguyên

- 18 < hoặc bằng x < hoặc bằng 17

\(\Rightarrow x\in\left\{-18;-17;-16;....;17\right\}\)

tổng \(x=-18+\left(-17\right)+\left(-16\right)+...+17=-18\)

- 27 < hoặc bằng x < hoặc bằng 27

\(\Rightarrow x\in\left\{-27;-26;-25;..;27\right\}\)

Tổng \(x=-27+\left(-26\right)+\left(-25\right)+...+27=0\)

câu 3 tìm x

- 16 + 23 + x = -16

\(x=-16-23+16\)

\(x=-23\)

2x _ 35 = 15

\(2x=15+35\)

\(2x=50\)

\(x=25\)

3x + 17 = 12

\(3x=29\)

\(x=\frac{29}{3}\)

dấu giá trị tuyệt đối x - 1 dấu giá trị tuyệt đối = 0

\(\Rightarrow x-1=0\)

\(x=1\)

- 13 nhân dấu giá trị tuyệt đối  x dấu giá trị tuyệt đối = -26

\(|x|=-26:\left(-13\right)\)

\(|x|=2\)

\(\Rightarrow x\in\left\{\pm2\right\}\)

câu 4 tính hợp lí

35 nhân 18 _ 5 nhân 7 nhân 28

\(=35.18-35.28\)

\(=35.\left(18-28\right)\)

\(=35.\left(-10\right)\)

\(=-350\)

45 _ 5 nhân ( 12 + 9 )

\(=45-5.21\)

\(=45-105=-60\)

24 nhân ( 16 _ 5 ) _ 16 nhân ( 24 _ 5 )

\(=24.16-24.5-16.24+16.5\)

\(=24.\left(16-16\right)+5.\left(-24+16\right)\)

\(=24.0+5.\left(-8\right)\)

\(=0-40=-40\)

29 nhân ( 19 _ 13 ) _ 19 nhân ( 29 _ 13 )

\(=29.19-29.13-19.29+19.13\)

\(=19.\left(29-29\right)+13.\left(-29+19\right)\)

\(=19.0+13.\left(-10\right)\)

\(=0+\left(-130\right)=-130\)

31 nhân ( -18 ) + 31 nhân ( -81 ) _ 31

\(=31.\left[\left(-18\right)+\left(-81\right)-1\right]\)

\(=31.\left(-100\right)=-3100\)

( - 12) nhân 47 + ( -12 ) nhân 52 + ( -12 )

\(=\left(-12\right).\left(47+52+1\right)\)

\(=\left(-12\right).100=-1200\)

13 nhân ( 23 + 22 ) _ 3 nhân ( 17 + 28 )

\(=13.45-3.45\)

\(=45.\left(13-3\right)\)

\(=45.10=450\)

- 48 + 48 nhân ( -78 ) + 48 nhân ( -21)

\(=48.\left(-1-78-21\right)\)

\(=48.\left(-100\right)\)

\(=-4800\)

b: Ta có: \(\dfrac{12}{5}:x+\dfrac{4}{3}=3+\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{12}{5}:x=3-\dfrac{2}{3}=\dfrac{7}{3}\)

hay \(x=\dfrac{12}{5}:\dfrac{7}{3}=\dfrac{36}{35}\)

1) = 35 . 18 - 35 . 18 = 0

2) = 45 - 5 . 12 + 5 . 9 = 45 - 60 + 45 = 30

3) = 24 . 16 - 24 . 5 - 16 . 24 - 16 . 5

= (24 . 16 - 16 . 24) - 5 (24 - 16)

= 0 - 5 . 8 = 0 - 40 = -40

4) = 29 . 19 - 29 . 13 - 19 . 29 - 19 . 13

= (29 . 19 - 29 . 19) - 13 (29 - 19)

= 0 - 13 . 10 = 0 - 130 = -130

5) = 31 . (-18) + 31 . (-81) - 31 . 1

= 31 [(-18) + (-81) - 1]

= 31 . (-100) = -3100

6) = (-12) . 47 + (-12) . 52 + (-12). 1

= (-12) . (47 + 52 + 1)

= (-12) . 100 = -1200

7) = 13 . 45 - 3 . 45

= 45 (13 - 3)

= 45 . 10 = 450

8) = (-48) + 48 . (-78) + 48 . (-21)

= (-48) . 1 + 48 . (-78) + 48 . (-21)

= 48 . (-1) + 48 . (-78) + 48 . (-21)

= 48 . [(-1) + (-78) + (-21)]

= 48 . (-100) = -4800

1) 35x18-5x7x18

= 35x18-35x18

= 35x(18-18)

= 35x0=0

3) 24.(16-5)-16.(24-5)

= 24.16-24.5-16.24-16.5

=[24.16-16.24]-[24.5-16.5]

= [ 24. (16-16)]- [(24-16).5]

= [24.0]-[8.5]

= 0-40=-40

4) 29.(19-13)-19.(29-13)

=29.19-29.13-19.29-19.13

=[ 29.19-19.29]-[ 29.13-19.13]

= [ 29.(19-19)]-[(29-19).13]

=[29.0]-[10.13]

= 0-130= -130

5) 31.(-18)+31.(-81)-31

= 31.(-18)+31.(-81)-31.1

= 31.[(-18)+(-81)-1]

=31.(-100)

= -3100

6);7);8 tương tự 4);5);6)