a.

\(10-2\left(4-3x\right)=-4\)

\(\Leftrightarrow2\left(4-3x\right)=10+4\)

\(\Leftrightarrow2\left(4-3x\right)=14\)

\(\Leftrightarrow4-3x=7\)

\(\Leftrightarrow3x=-3\)

\(\Leftrightarrow x=-1\)

b.

\(-12+3\left(-x+7\right)=-18\)

\(\Leftrightarrow3\left(-x+7\right)=-18+12=-6\)

\(\Leftrightarrow-x+7=-6:3=-2\)

\(\Leftrightarrow x=9\)

c.

\(-45:5.\left(-3-2x\right)=3\)

\(\Leftrightarrow-9.\left(-3-2x\right)=3\)

\(\Leftrightarrow-3-2x=-\dfrac{1}{3}\)

\(\Leftrightarrow2x=-\dfrac{8}{3}\)

\(\Leftrightarrow x=-\dfrac{4}{3}\notin Z\left(loại\right)\)

Câu này em ghi sai đề?

d.

\(3x-28=x+36\)

\(\Leftrightarrow2x=28+36\)

\(\Leftrightarrow2x=64\)

\(\Leftrightarrow x=32\)

e.

\(\left(-12\right)^2.x=56+10.13x\)

\(\Leftrightarrow144x=56+130x\)

\(\Leftrightarrow144x-130x=56\)

\(\Leftrightarrow14x=56\)

\(\Leftrightarrow x=4\)

a ) x :   − 9   =   − 54  x  =   − 54 .   − 9  x  = 486

b ) x  :   − 12   =  18  x  =  18 .   − 12  x  = − 216

c ) x :   − 5   =   − 19  x  =   − 19 . − 5  x  =  95

1) x-12=(-8)+(-17)
    x-12=(-25)
    x      = (-25)+12
    x      = (-13)

Giải:

a) \(\dfrac{-1}{5}\le\dfrac{x}{8}\le\dfrac{1}{4}\) 

\(\Rightarrow\dfrac{-8}{40}\le\dfrac{5x}{40}\le\dfrac{10}{40}\) 

\(\Rightarrow5x\in\left\{0;\pm5;10\right\}\) 

\(\Rightarrow x\in\left\{0;\pm1;2\right\}\) 

b) \(\dfrac{4}{x-6}=\dfrac{y}{24}=\dfrac{-12}{18}\) 

\(\Rightarrow\dfrac{4}{x-6}=\dfrac{-12}{18}\) 

\(\Rightarrow-12.\left(x-6\right)=4.18\) 

\(\Rightarrow-12x+72=72\) 

\(\Rightarrow-12x=72-72\) 

\(\Rightarrow-12x=0\) 

\(\Rightarrow x=0:-12\) 

\(\Rightarrow x=0\) 

\(\Rightarrow\dfrac{y}{24}=\dfrac{-12}{18}\) 

\(\Rightarrow y=\dfrac{-12.24}{18}=-16\) 

c) \(\dfrac{x+46}{20}=x.\dfrac{2}{5}\) 

\(\dfrac{x+46}{20}=\dfrac{2x}{5}\) 

\(\Rightarrow5.\left(x+46\right)=2x.20\) 

\(\Rightarrow5x+230=40x\) 

\(\Rightarrow5x-40x=-230\) 

\(\Rightarrow-35x=-230\) 

\(\Rightarrow x=-230:-35\) 

\(\Rightarrow x=\dfrac{46}{7}\) 

Chúc bạn học tốt!

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) \(-28-7|-3x+15|=-70\)

\(\Rightarrow7|-3x+15|=42\)

\(\Rightarrow|-3x+15|=6\)

\(\Rightarrow|3\left(5-x\right)|=6\)

\(\Rightarrow|3|.|5-x|=6\)

\(\Rightarrow3|5-x|=6\)

\(\Rightarrow|5-x|=2\)

\(\Rightarrow\orbr{\begin{cases}5-x=2\\5-x=-2\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=3\\x=7\end{cases}}\)

Vậy \(x\in\left\{3;7\right\}\)

b) \(|18-2|-x+5||=12\)

\(\Rightarrow\orbr{\begin{cases}18-2|-x+5|=12\\18-2|-x+5|=-12\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2|5-x|=6\\2|5-x|=30\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}|5-x|=3\left(1\right)\\|5-x|=15\left(2\right)\end{cases}}\)

Từ \(\left(1\right):\Rightarrow\orbr{\begin{cases}5-x=3\\5-x=-3\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=2\\x=8\end{cases}}\)

Từ \(\left(2\right):\Rightarrow\orbr{\begin{cases}5-x=15\\5-x=-15\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-10\\x=20\end{cases}}\)

Vậy \(x\in\left\{2;8;-10;20\right\}\)

c) \(12-2\left(-x+3\right)^2=-38\)

\(\Rightarrow2\left(3-x\right)^2=50\)

\(\Rightarrow\left(3-x\right)^2=100\)

\(\Rightarrow\orbr{\begin{cases}3-x=10\\3-x=-10\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-7\\x=13\end{cases}}\)

Vậy \(x\in\left\{-7;13\right\}\)

d) \(-20+3\left(2x+1\right)^3=-101\)

\(\Rightarrow3\left(2x+1\right)^3=-81\)

\(\Rightarrow\left(2x+1\right)^3=-27\)

\(\Rightarrow2x+1=-3\)

\(\Rightarrow2x=-4\)

\(\Rightarrow x=-2\)

Vậy \(x=-2\)

Trả lời:

a, -28 - 7| -3x + 15 | = -70

=> 7| -3x + 15 | = 42

=> | -3x + 15 | = 6

=> -3x + 15 = 6 hoặc -3x + 15 = -6

=>   -3x = -9                    -3x = -21

=>  x = 3                            x = 7

Vậy x = 3; x = 7

b, | 18 - 2 | -x + 5 || = 12

=> 18 - 2| -x + 5 | = 12 hoặc 18 -  2| -x + 5 | = -12

=> 2 | -x + 5 | = 6   hoặc    2 | -x + 5 | = 30

=> | -x + 5 | = 3    hoặc      | -x + 5 | = 15

=>  -x + 5 = 3 hoặc -x + 5 = -3 hoặc -x + 5 = 15 hoặc -x + 5 = -15

=>  x = 2                     x = 8                  x = -10               x = 20

Vậy x \(\in\){ 2; 8; -10; 20 }

c, 12 - 2.( -x + 3 )² = -38

=> 2.( -x + 3 )² = 50

=> ( -x + 3 )² = 25

=> -x + 3 = 5 hoặc -x + 3 = -5

=>   x = -2                x = 8

Vậy x = -2; x = 8

d, -20 + 3.( 2x + 1 )³ = -101

=> 3.( 2x + 1)³ = -81

=> ( 2x + 1 )³ = -27

=> 2x + 1 = -3 

=> 2x = -4

=> x = -2

Vậy x = -2

=> x = 1

\(a,\dfrac{x}{5}=\dfrac{-18}{10}\\ \Rightarrow x=-\dfrac{18}{10}.5\\ \Rightarrow x=-9\\ b,\dfrac{6}{x-1}=\dfrac{-3}{7}\\ \Rightarrow6.7=-3\left(x-1\right)\\ \Rightarrow42=-3x+3\\ \Rightarrow42+3x-3=0\\ \Rightarrow3x+39=0\\ \Rightarrow3x=-39\\ \Rightarrow x=-13\\ c,\dfrac{y-3}{12}=\dfrac{3}{y-3}\\ \Rightarrow\left(y-3\right)^2=36\\ \Rightarrow\left[{}\begin{matrix}y-2=6\\y-2=-6\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}y=8\\y=-4\end{matrix}\right.\)

\(d,\dfrac{x}{25}=\dfrac{-5}{x^2}\\ \Rightarrow x^3=-125\\ \Rightarrow x^3=\left(-5\right)^3\\ \Rightarrow x=-5\)

1.

7.5.(-2)=12.(-2)=-24

-54-18=-72

2.

x+4=-12

    x=-12-4

    x=-16

Vậy x=-16

3.

3x-5=-7-13

3x-5=-20

3x=-20+5

3x=-15

  x=-15:3

  x=-5

Vậy x=-5