\(-7\left(3x-5\right)+2\left(7x-14\right)=28\)

\(\Leftrightarrow-21x+35+14x-28=28\)

\(\Leftrightarrow-7x=21\)

\(\Leftrightarrow x=-3\)

Vậy : \(x=-3\)

- 7 ( 3x - 5 ) + 2 ( 7x - 14 ) = 28

=>  - 21x + 35 + 14x  - 28 = 28

=> - 7x   + 7 = 28

=> 7 (x - 1 ) = 28

=> x - 1 = 4 

=> x = 3

Vậy x = 3

Bài làm

-7(3x-5)+2(7x-14) = 28

=> -21x+ 35 + 14x - 28 = 28

=> -7x + 7 = 28

=> -7x = 21

=> x = -3

VẬY..

a/ 7x(2x+x) - 7x(x+3) =14

7x(2x+x-x-3)=14

x(2x-3)=2

=> x=2

Trả lời :

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Hok tốt nha !

a) -5 . (2 - x) + 4(x - 3) = 10x - 15

-10 + 5x + 4x -12 = 10x - 15

5x + 4x - 10x = -15 + 10 + 12

-x = 7

x = -7

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

15 - 10x + 5x - 20 = 6 - 4x

-10x + 5x + 4x = 6 - 15 + 20

-x = 11

x = -11

c) - 7 . (3x - 5) + 2 . (7x - 14) = 28

-21x + 35 + 14x - 28 = 28

-21x + 14x = 28 - 35 + 28

-7x = 21

x = 21 : (-7)

x = -3

d) 4 . (x - 5) - 3 . (x + 7) = 5 . (-4)

4x - 20 - 3x - 21 = -20

4x - 3x = -20 + 20 + 21

x = 21

e) 5 . (4 - x) - 7. (-x + 2) = 4 - 9 + 3

20 - 5x + 7x - 14 = -2

-5x + 7x = -2 - 20 + 14

2x = -8

x = -8 : 2

x = -4

Đúng 100%

câu c

- 7 ( 3x - 5 ) + 2 ( 7x - 14 ) = 28

- 21x + 35 + 14x - 28 = 28

 21x - 14x = 35 - 28 - 28

7x = - 21

x = ( - 21) : 7

x = - 3 

a, -5 .(2- x) +4 (x-3) =10x -15
<=> -19 +5x +4x-12 -10x +15=0
<=> -x=16
<=>x=16
b, 5(3-2x) +5.(x-4)=6-4x
<=> 15-10x +5x-20 -6+4x=0
<=> -x=-11
<=> x=11
c, -7.(3x-5) +7.(7x -14)=28
<=> -21x +35+49x -98-28=0
<=>28x=-91
<=>x= -\(\frac{13}{4}\)
d, 4.(x-5) -3.(x+7)=5.(-4)
<=>4x-20-3x-21=-20
<=>x=21
e,5.(4-x)-7.(-x+2)=4-9+3
<=>20x -5x +7x -14= -2
<=>22x=12
<=>x=\(\frac{6}{11}\)
P tự kết luận nhé k hiểu hay mk sai chỗ nào p pảo mk nhé

1.a)x=-21

b)x=87

c)x=20,5

Bài 2: 

x = (-2)

y = 3

cho mình cách giải với các bạn ơi

\(\frac{3}{7}\left(7x+\frac{2}{3}\right)-2\left(\frac{5}{14}-3x\right)=\frac{15}{5}\)

\(\Leftrightarrow3x+\frac{2}{7}-\frac{5}{7}+6x=3\)

\(\Leftrightarrow9x=\frac{24}{7}\)

\(\Leftrightarrow x=\frac{8}{21}\)

\(\frac{3}{7}.\left(7x+\frac{2}{3}\right)-2.\left(\frac{5}{14}-3x\right)=\frac{15}{5}\)

\(\Leftrightarrow3x+\frac{2}{7}.x-\frac{5}{7}+6x=3\)

\(\Leftrightarrow\frac{65}{7}.x-\frac{5}{7}=3\)

\(\Leftrightarrow\frac{65}{7}.x=3+\frac{5}{7}\)

\(\Leftrightarrow\frac{65}{7}.x=\frac{26}{7}\)

\(\Leftrightarrow x=\frac{26}{7}:\frac{65}{7}\)

\(\Leftrightarrow x=\frac{2}{5}\)

 3/7.(7x+2/3)-2.(5/14-3x)=15/5

\(\Leftrightarrow3x+\frac{2}{7}.x-\frac{5}{7}+6x=3\)

\(\Leftrightarrow\frac{65}{7}.x-\frac{5}{7}=3\)

\(\Leftrightarrow\frac{65}{7}.x=\frac{26}{7}\)\(\Leftrightarrow x=\frac{2}{5}\)

Vậy x =\(\frac{2}{5}\)

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

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

                                4x - 72 = 8

                                       4x = 8 + 72

                                       4x = 80

                                         x = 20

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

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

                                                - x - 52 = 0

                                                         x = - 52

c,  7x . ( 2 + x ) - 7x . ( x + 3 ) = 14

                7x . ( 2 + x - x - 3 ) = 14

                              7x . ( - 1 ) = 14 

                                         7x = 14 : ( - 1 )

                                         7x = - 14 

                                           x = - 2

d, 2 . ( 5 + 3x ) + x = 31

           10 + 6x + x = 31

                 10 + 7x = 31

                         7x = 31 - 10

                          7x = 21

                            x = 3

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

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

4x+-72=8

4x=80

x=80:4

x=20

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

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

(-8x+8x)+-36+-3+x-13=0

0+-52+x=0

x=0-(-52)

x=-52

c)7x(2+x)-7x(x+3)=14

14x+7x²

a)\(\frac{x-1}{x-5}=\frac{6}{7}\) điều kiện : x khác 5

<=>7x-7=6x-30<=> x=-23

b) \(\frac{12-7x}{-13}=\frac{4-3x}{-5}\)

<=> -60+35x=-52+39x

<=> 4x=-8

<=> x=-2