a) \(x+5=20-\left(12-7\right)\)

\(\Rightarrow x+5=20-5\)

\(\Rightarrow x+5=15\)

\(\Rightarrow x=15-5\)

\(\Rightarrow x=10\)

b) \(15-\left(3+2x\right)=2^2\)

\(\Rightarrow3+2x=15-4\)

\(\Rightarrow3+2x=11\)

\(\Rightarrow2x=11-3\)

\(\Rightarrow2x=8\)

\(\Rightarrow x=\dfrac{8}{2}\)

\(\Rightarrow x=4\)

c) \(-11-\left(19-x\right)=50\)

\(\Rightarrow19-x=-11-50\)

\(\Rightarrow19-x=-61\)

\(\Rightarrow x=61+19\)

\(\Rightarrow x=80\)

d) \(159-\left(25-x\right)=43\)

\(\Rightarrow25-x=159-43\)

\(\Rightarrow25-x=116\)

\(\Rightarrow x=25-116\)

\(\Rightarrow x=-91\)

e) \(\left(79-x\right)-43=-\left(17-52\right)\)

\(\Rightarrow\left(79-x\right)-43=52-17\)

\(\Rightarrow79-x-43=35\)

\(\Rightarrow36-x=35\)

\(\Rightarrow x=1\)

f) \(\left(7+x\right)-\left(21-13\right)=32\)

\(\Rightarrow7+x-8=32\)

\(\Rightarrow x-1=32\)

\(\Rightarrow x=32+1\)

\(\Rightarrow x=33\)

g) \(-x+20=-15+8+13\)

\(\Rightarrow-x+20=6\)

\(\Rightarrow x=20-6\)

\(\Rightarrow x=14\)

h) \(-\left(-x+13-142\right)+18=55\)

\(\Rightarrow x-13+142+18=55\)

\(\Rightarrow x+147=55\)

\(\Rightarrow x=55-147\)

\(\Rightarrow x=-92\)

d) |2x – 5| –7 = 22

| 2x -5 | = 22+7

| 2x -5 | = 29

TH1: 2x-5 = -29

2x = -29+5

2x= -24

x= -24:2

x= -12

TH2: 2x -5 =29

2x = 29+5

2x= 34

x= 34:2

x= 17 

Vậy...

a) x – 14 = 3x + 18

x -14 - 3x = 18

-2x -14 =18

-2x = 18-14

-2x = 4

x = 4:( -2) 

x= -2

Vậy...

b) 2 ( x – 5 ) – 3 ( x – 4 ) = -6 + 15.(- 3)

2 ( x – 5 ) – 3 ( x – 4 ) = -51

2x -10 - 3x -12 = -51

-x -  [ -10 - ( -12) ] = -51

-x - 2 = -51

-x = -51+2

-x = -49

Vậy...

Mk thử lại thấy nó sai sai nhưng ko biết sửa sao????

c) ( x + 7 ) ( x – 9) = 0 

=> x+ 7 = 0 hoặc x- 9 = 0

Nếu x+7 = 0 thì x = 0-7 => x = -7

Nếu x-9 = 0 thì x = 0+9=> x = 9

Vậy...

1. a) 2 + (-25) + 41 + (-2) + 25 + (-41)

     = 2 - 25 + 41 - 2 + 25 -41

  = ( 2 -2 ) + ( 25 - 25 ) + ( 41 - 41 )

= 0 + 0 + 0

= 0

b) 10 + (-17) + 5 + (-7) + 17 + (-15)

= 10 - 17 + 5 - 7 + 17 - 15

= ( 10 + 5 -15 ) + ( 17 -17 ) - 7

= 0 + 0 - 7

= -7

c) (-22) + (-14) + 17 + (-24) + 13 + 30

= -22 - 14 + 17 - 24 + 13 + 30

= ( -22 - 14 - 24 ) + ( 17 + 13 + 30)

= -60 + 60

= 0

2 a) -22 < x < 23

 x thuộc { -21 ;-20;-19;-18;-17;-16;-15;-14;-13;-12;-11;-10;-9;-8;-7;-6;-5;-4;-3;-2;-1;0;1;2;3;4;5;6;7;8;9;10;11;12;13;14;15;16;17;18;19;20;21;22}

Tổng các số nguyên trên là

( -21 ) + ( -20 ) + ( -19 ) + ..... + 22

= 22 + [( -21 ) +21 ] + [( -20) + 20] + ..... 0

= 22 + 0 + 0 + ... + 0

= 22

b) -36 < x < 34

Tương tụ câu a)

nguyễn hiền phần a trình bày sai r nhé lẽ ra là 

a) 2 + (-25) + 41 + (-2) + 25 + (-41)

= [(2 + (-2)] + [(-25) + 25] + [41 + (-41)]

=       0       +         0       +       0

= 0

k dùm nhem các anh ; chị ; em

a, 75 - 5 . ( 15 - 10 ) - ( -60 ) = 75 - 5 . 5 + 60 = 135 - 25 = 110

b, 136 - ( -7 ) + 6 - 23 - 36 = 136 + 7 + 6 - 23 - 36 = ( 136 - 36 ) + ( 7 + 6 - 23 ) = 100 - 10 = 90

c, ( -15 - 17 ) . ( -15 + 7 ) = -32 . ( -8 ) = 256

d, ( -9 - 18 ) : ( -9 ) = -27 : ( -9 ) = 3

Bài 2:

a, 2x - 17 = ( -3x - 18 )

<=> 2x + 3x = 17 - 18

<=> 5x = -1

<=> x = -1/5

b, ( 13 - IxI ) + 15 = 20

<=> 13 - |x| = 5

<=> |x| = 8

<=> x = 8 hoặc x = -8  

c, Ix + 5I - ( x + 5 ) = 0

<=> |x + 5| = x + 5 

Đk: x + 5 ≥ 0 => x ≥ -5

\(\Leftrightarrow\orbr{\begin{cases}x+5=x+5\\x+5=-x-5\end{cases}\Leftrightarrow}\orbr{\begin{cases}0x=0\\2x=-10\end{cases}\Leftrightarrow}\orbr{\begin{cases}x\ge-5\\x=-5\end{cases}}\)

Vậy  x ≥ -5

Tìm số nguyên x, biết:
1) -16 + 23 + x = - 16

7+x=-16

    x=-16-7

    x=-23
2) 2x – 35 = 15

2x=15+35

2x=50

  x=50:2

  x=25
3) 3x + 17 = 12

3x=12-17

3x=-5

  x=-5/3
4) (2x – 5) + 17 = 6

2x-5=6-17

2x-5=-11

2x=-11+5

2x=-6

  x=-6:2

  x=-3
5) 10 – 2(4 – 3x) = -4

2(4-3x)=10-(-4)

2(4-3x)=14

4-3x=14:2

4-3x=7

3x=4-7

3x=-3

  x=-3:3

  x=-1
6) - 12 + 3(-x + 7) = -18

3(-x+7)=-18-(-12)

3(x+7)=-6

x+7=-6:3

x+7=-2

    x=-2-7

    x=-9

tự đi mà làm

a, 7\(x\).(\(x\) - 10) = 0

   \(\left[{}\begin{matrix}7x=0\\x-10=0\end{matrix}\right.\)

    \(\left[{}\begin{matrix}x=0\\x=10\end{matrix}\right.\)

Vậy \(x\in\) {0; 10}

b, 17.(3\(x\) - 6).(2\(x\) - 18) = 0

    \(\left[{}\begin{matrix}3x-6=0\\2x-18=0\end{matrix}\right.\)

    \(\left[{}\begin{matrix}3x=6\\2x-18=0\end{matrix}\right.\)

     \(\left[{}\begin{matrix}x=6:3\\x=18:2\end{matrix}\right.\)

       \(\left[{}\begin{matrix}x=2\\x=9\end{matrix}\right.\)

c, (4 - 2\(x\)).(\(x\) - 3) = 0

    \(\left[{}\begin{matrix}4-2x=0\\x-3=0\end{matrix}\right.\)

    \(\left[{}\begin{matrix}2x=4\\x=3\end{matrix}\right.\)

    \(\left[{}\begin{matrix}x=4:2\\x=3\end{matrix}\right.\)

     \(\left[{}\begin{matrix}x=2\\x=3\end{matrix}\right.\)

    Vậy \(x\in\) {2; 3}

1,\(54.\left(23-11\right)+23.\left(-22-54\right)\)

\(=54.12+23.\left(-76\right)\)

\(=648-1748\)

\(=-1100\)

2,\(-7+2x=-17-\left(-36\right)\)

\(=>-7+2x=-17+36\)

\(=>-7+2x=19\)

\(=>2x=19+7=26\)

\(=>x=\frac{26}{2}=13\)

3,\(5⋮2a+3\)

\(=>2a+3\inƯ\left(5\right)\)

\(=>2a+3\in\left\{-1;-5;1;5\right\}\)

\(=>2a\in\left\{-4;-8;-2;2\right\}\)

\(=>a\in\left\{-2;-4;-1;1\right\}\)

Vậy ...

54 . ( 23 - 11 ) + 23 . ( -22 - 54 )

=54.23-54.11+23.-22-23.54

=-54.11+23.-22

=-22(27+23)

=-22.50

=-1100

-7 + 2x = -17 - ( -36 ) 

-7+2x=-17+36

-7+2x+17-36=0

-26+2x=0

2x=26

x=13

Vậy x=13

Để \(5⋮\left(2a+3\right)\Leftrightarrow\left(2a+3\right)\inƯ\left(5\right)\)

\(\Leftrightarrow\left(2a+3\right)\in\left\{\pm1;\pm5\right\}\)

\(\Leftrightarrow a\in\left\{-1;-2;1;-4\right\}\)

Bài 1:

54. (23-11) + 23.(-22-54) = 54.23-11.54 -23.22 - 54.23

                                        = (54.23-54.23) -(11.54+23.22)

                                        = 0 - (11.54 +23.11.2)

                                        = 0 - 11.(54+23.2)

                                        = 0 - 11. 100

                                       = -1100

Bài 2:                        -7 +2x = -17 -(-36)

                                  -7 +2x = 19

                                       2x  = 26

                                         x  = 13

Bài 3:        Ta có: \(5⋮\left(2a+3\right)\) 

\(\Rightarrow2a+3\inƯ\left(5\right)\)

\(\Rightarrow2a+3\in\left\{-5;-1;1;5\right\}\)

\(\Rightarrow2a\in\left\{-8;-4;-2;2\right\}\)

\(\Rightarrow a\in\left\{-4;-2;-1;1\right\}\)