Question

7) | 1/4x - 3/4| = 4/ 5 x- 2/5

8) | 2x-1| =x

9) | x+ 2| = 2x

Answer 1

7) | 1/4x - 3/4| = 4/ 5 x- 2/5

Th1:

1/4x - 3/4 = 4/ 5 x- 2/5

1/4x - 4/5x = -2/5 + 3/4

-11/20x = 7/20

x= -7/11

Th2: 

 1/4x - 3/4 = -(4/ 5 x- 2/5)

1/4x + 4/5x = 3/4 +  2/5

 21/20x = 23/20

x= 23/21

Vậy...

8) | 2x-1| =x

Th1:

2x -1 = x

x= 1

Th2:

2x -1 = -x

3x = 1

x= 1/3

Vậy...

9) | x+ 2| = 2x

Th1:

x+2 = 2x

x= 2

Th2:

x+2 = -2x

3x =2

x= 2/3

Vậy...

Answer 2

7) | 1/4x - 3/4| = 4/ 5 x- 2/5

Th1:

1/4x -3/4 = 4/5x -2/5

1/4x - 4/5x = -2/5 + 3/4

(1/4 - 4/5)x = 7/20

-11/20x = 7/20

x= 7/20 : (-11/20)

x= -7/11

Th2:

1/4x - 3/4 = -(4/5x - 2/5)

1/4x - 3/4 = -4/5x + 2/5

 1/4x + 4/5x = 2/5 + 3/4

(1/4 + 4/5)x = 23/20

21/20x = 23/20

x= 23/20 : 21/20

x= 23/21

8) | 2x-1| =x

Th1:

2x -1 = x

2x - x= 1

(2-1)x=1

x= 1

Th2:

2x -1 = -x

2x +x = 1

(2+1)x =1

3x =1

x= 1:3

x= 1/3

Vậy...

Còn câu 9 chiều gửi cho

Answer 3

9) | x+ 2| = 2x

Th1:

x+2 = 2x

2= 2x -x 

<=> 2x -x =2

(2-1)x=2

x=2

Th2:

x+2 = -2x

x + 2x =-2

(1+2)x = -2

3x = -2

x=-2 : 3

x= -2/3

(câu 9 này mới đúng nhé, cái kia bị thiếu dấu)

Answer 4