a)15 - x = 7 - (-2)

15-x = 9

x = 15 - 9

x = 6

b) 11 - ( 15 + 11 ) = x - (25 - 9 )

11 - 26 = x - 16

-15 = x - 16

-15 + 16 = x 

1 = x

c) ( 7 - x ) - ( 25 + 7 ) = 9 - 25

(7-x) - 32 = -16

(7-x) = -16 + 32

7-x = 16

x = 7-16

x = -9

a,11-(15+21)=x-(25-9)

      11-15-21=x-25+9

               -x=-25+9-11+15+21

               -x=9

                x=-9

b,9-25=(7-x)-(25+7)

    -16=7-x-32

      x=7-32+16

     x=-9

\(A)9-25=\left(7-x\right)-\left(25+7\right)\)

\(\Rightarrow9-25=7-x-25-7\)

\(\Rightarrow x=7-25-7-9+25\)

\(\Rightarrow x=\left(7-7\right)+\left(25-25\right)-9\)

\(\Rightarrow x=0+0-9\)

\(x=-9\)

\(B)x-\left(17-x\right)=x-7\)

\(\Rightarrow x-17+x=x-7\)

\(\Rightarrow2x-17=x-7\)

\(\Rightarrow x=-7+17\)

\(x=10\)

a, x-(17-x)=x-7

x-17+x = x-7

(x+x) - 17 = x - 7

2x - 17 = x - 7

2x - x = -7 + 17

1x = 10

x = 10

vậy_____

b, 9-25 = (7-x)-25+7

-16 = 7-x - 25 + 7

-16 = 7-x - (25-7)

-16 = 7-x - 18

-16 + 18 = 7 - x

2 = 7- x

2 - 7 = x

-5 = x

vậy____

x - ( 17 - x ) = x - 7

x - 17 + x = x - 7

x + x - x = 17 - 7

x = 10

9 - 25 = ( 7 - x ) - 25 +7

-16 = 7 - x - 25 + 7 

- 16 = 7 - 32 - x 

- 16 = -25 - x

x = - 25 - ( - 16 )

x = -9

a, x-(17-x)=x-7

x-17+x = x-7

(x+x) - 17 = x - 7

2x - 17 = x - 7

2x - x = -7 + 17

1x = 10

x = 10

x=10

b, 9-25 = (7-x)-25+7

-16 = 7-x - 25 + 7

-16 = 7-x - (25-7)

-16 = 7-x - 18

-16 + 18 = 7 - x

2 = 7- x

2 - 7 = x

-5 = x

a) (-4).(x+41)=400

 => x + 41 = 400 : ( -4)

=> x + 41 = -100

=> x = -100 - 41

=> x = -141

b) 9-25=(7-x)-(25+7)

 => -16 = ( 7 - x ) - 32

=> 7 - x = 32 - ( -16 ) 

=> 7 - x = 48

=> x = 7 - 48

=> x = -41

a, 11 - ( 15 + 11 ) = x - ( 25 - 9 )

11-15-11=x-25+9

-15=x-16

x=1

b, 2 - x = 17 - ( - 5 )

2-x=22

x=-20

c, x - 12 = ( - 9 ) - 15

x-12=-24

x=-12

d, 9 - 25 = ( 7 - x ) - ( 25 + 7 )

(7-x)-32=-16

7-x=16

x=-9

#H

a, 1-[15+11­] = x-[25-9]

1-16=x-16

-15=-x-16

x=-15+16

x=1

b,2-x=17-[-5]

2-x=17+5

2-x=22

x=2-22

x=-20

c, x-12=[-9­]-15

x-12=-24

x=-24+12

x=-12

d,9-25=[ 7- x­] -[25+7]

-16=[7-x]-32

[7-x]-32=-16

7-x=-16+32

7-x=16

x=7-16

x=-9

a) x - (17 - 8) = 5 + (10 - 3x)

x - 17 + 8 = 5 + 10 - 3x

x + 3x = 5 + 10 + 17 - 8

4x = 24

x = 24 : 4

x = 6

b) 25 - (30 + x) = x - (27 - 8)

25 - 30 - x = x - 27 + 8

-x - x = -27 + 8 - 25 + 30

-2x = -14

x = (-14) : (-2)

x = 7

c) (x - 12) - 15 = (20 - 7) - (18 + x)

x - 12 - 15 = 20 - 7 -18 - x

x + x = 20 - 7 - 18 + 12 + 15

2x = 22

x = 22 : 2

x = 11

d) 9 - 25 = (7 - x) - (25 + 7)

9 - 25 = 7 - x - 25 - 7

x = 7 - 25 - 7 - 9 +25

x = -9

\(\left|x\right|-7=9\Rightarrow\left|x\right|=16\)

\(\Rightarrow x=\pm16\)

\(9-25=\left(7-x\right)-\left(25+7\right)\)

\(9-25=7-x-25-7\)(tính chất mở ngoặc đôie dấu)

\(9-25=-x-25\)

\(\Rightarrow\)\(9=-x\)

\(\Rightarrow x=-9\)

Vậy x = - 9

\(a.\)

\(\left|x\right|-7=9\)

\(\Rightarrow\left|x\right|=9+7=16\)

\(\Rightarrow\left[{}\begin{matrix}x=16\\x=-16\end{matrix}\right.\)

\(b.\)

\(9-25=\left(7-x\right)-\left(25+7\right)\)

\(\Leftrightarrow9-25=7-x-25-7\)

\(\Rightarrow-16=-x-25\)

\(\Rightarrow-x=-16+25=9\)

\(\Rightarrow x=-9\)