5.(x+7)=3.(2-x)

=>5x+35=6-3x

=>5x+3x=6+41

=>8x=47

=>x=47:8=47/8

\(12\left(x-3\right)=5\left(x-1\right)+4\)

\(\Rightarrow12x-36=5x-5+4\)

\(\Rightarrow12x-5x=-5+4+36\)

\(\Rightarrow7x=35\)

\(\Rightarrow x=5\)

\(-6\left(x-7\right)+2\left(x+10\right)=x-18\)

\(-6x+42+2x+20=x-18\)

\(-6x+2x-x=-18-20-42\)

\(-5x=-80\)

\(x=16\)

\(7\left(2x-1\right)-12\left(x-5\right)=3\)

\(\Rightarrow14x-7-12x+60=3\)

\(\Rightarrow14x-12x=3-60+7\)

\(\Rightarrow2x=-50\)

\(\Rightarrow x=-25\)

\(\left|2x-1\right|=17\)

\(\Leftrightarrow\orbr{\begin{cases}2x-1=17\\2x-1=-17\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=9\\x=-8\end{cases}}\)

\(\left|8-3x\right|=14\)

\(\Leftrightarrow\orbr{\begin{cases}8-3x=14\\8-3x=-14\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=-2\\x=\frac{22}{3}\end{cases}}\)

a) 3x - 4 (2x-7) = 3x - 3

3x - 8x + 28 = 3x - 3

=> 3x - 8x - 3x = -3 -28

-8x = -31

x =  31/8

b) 3(2x-7) - (4-2x) = 2x -1

6x - 7 - 4 + 2x = 2x -1

=> 6x + 2x - 2x = -1 + 7+4

6x  = 10

x = 5/3

c) (x-2).(2x+12)=0

=> x -2 = 0 => x = 2

2x + 12 = 0 => 2x = -12 => x = -6

KL: x = 2 hoặc x = -6

\(3x-4\left(2x-7\right)=3x-3\)

\(\Leftrightarrow3x-8x+28=3x-3\)

\(\Rightarrow3x-8x-3x=-3-28\)

\(\Leftrightarrow-8x=-31\)

\(\Leftrightarrow x=\frac{31}{8}\)

Mấy câu kia dễ đổi dấu tự làm :)

a ) \(-5\times\left(-x+7\right)-3\times\left(-x-5\right)=-4\times\left(12-x\right)+48\)

\(\Leftrightarrow5x-35+3x+15=-48+4x+48\)

\(\Leftrightarrow5x-3x+4x=35-15-48+48\)

\(\Leftrightarrow2x=20\)

\(\Leftrightarrow x=10\)

b ) \(-2\times\left(15-3x\right)-4\times\left(-7x+8\right)=-5-9\times\left(-2x+1\right)\)

\(\Leftrightarrow-30+6x-28x-32=-5+18x-9\)

\(\Leftrightarrow6x-28x-18x=30+32-5-9\)

\(\Leftrightarrow-40x=48\)

\(\Leftrightarrow x=-1.2\)

C,D nưã bạn

 c, 7 . ( - x - 7 ) - 5 . ( - x - 3 ) = 12 . ( 3 - x)

<=> - 7x - 49  + 5x  + 15 = 36 - 12x

<=>  - 2x + 12x = 36 - 15 + 49

<=> 10 x = 70

<=> x = 7

Vẫy  x = 7

d, 5 . ( - 3x - 7 ) - 4 . ( - 2x - 11 ) = 7 . ( 4x + 10) + 9

<=> - 15x + 8x + 44 = 28x + 70 + 9

<=> - 7x + 44 = 28x + 79

<=> - 7x - 28x = 79 - 44

<=> - 35x = 35

<=> x = - 1

Vậy x = - 1

Hc tốt

2x+12=3(x-7)

2x+12=3x-21

3x-2x=12+21

x=33

vậy x=33

2x + 12 = 3 ( x - 7 )

2x + 13 = 3x - 3. 7 

2x + 13 = 3x - 21

- 3x + 2x = -13 - 21

-1x = -34

x = -34 : ( - 1 )

x = 34

2x+12=3x-21

=>3x-2x=12+21

=>x=33

\(2x+12=3.\left(x-7\right)\)

\(=>2x+12=3x-21\)

\(=>-x=-21-12=-33\)

\(=>x=33\)

2x+12=3.(x-7)

<=>2x+12=3x-21

<=>2x-3x=-21-12

<=>-x=-33

<=>x=33

Bài 1: 

a) Ta có: \(\dfrac{17}{6}-x\left(x-\dfrac{7}{6}\right)=\dfrac{7}{4}\)

\(\Leftrightarrow\dfrac{17}{6}-x^2+\dfrac{7}{6}x-\dfrac{7}{4}=0\)

\(\Leftrightarrow-x^2+\dfrac{7}{6}x+\dfrac{13}{12}=0\)

\(\Leftrightarrow-12x^2+14x+13=0\)

\(\Delta=14^2-4\cdot\left(-12\right)\cdot13=196+624=820\)

Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:

\(\left\{{}\begin{matrix}x_1=\dfrac{14-2\sqrt{205}}{-24}=\dfrac{-7+\sqrt{205}}{12}\\x_2=\dfrac{14+2\sqrt{2015}}{-24}=\dfrac{-7-\sqrt{205}}{12}\end{matrix}\right.\)

b) Ta có: \(\dfrac{3}{35}-\left(\dfrac{3}{5}-x\right)=\dfrac{2}{7}\)

\(\Leftrightarrow\dfrac{3}{5}-x=\dfrac{3}{35}-\dfrac{10}{35}=\dfrac{-7}{35}=\dfrac{-1}{5}\)

hay \(x=\dfrac{3}{5}-\dfrac{-1}{5}=\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)

ai giúp mik vs

Bài 3: 

a) Ta có: \(2x-3=x+\dfrac{1}{2}\)

\(\Leftrightarrow2x-x=\dfrac{1}{2}+3\)

\(\Leftrightarrow x=\dfrac{7}{2}\)

b) Ta có: \(4x-\left(x+\dfrac{1}{2}\right)=2x-\left(\dfrac{1}{2}-5\right)\)

\(\Leftrightarrow3x-\dfrac{1}{2}-2x+\dfrac{1}{2}-5=0\)

\(\Leftrightarrow x=5\)

a)

 13/4+x=2

          x=2-13/4

         x=-5/4

b)

 2x.17/12=3/7

 2x          =3/7;17/12

 2x         =36/119

  x           =36/119 : 2

  x           =18/119

c)

 2x.17/12=19/7

 2x         =19/7:17/12

 2x         =228/119

   x         =228/119;2

   x         =114/119

d)

 1/2x + 5/6=-3

 1/2x         =-3-5/6

 1/2x         =-23/6

     x          =-23/6:1/2

    x          =-23/3