nhưng làm gì 

a)x=15+5=20

b)x=(15-17):2=-1

c)=>x-2=+-3

th1x=-3+2=-5

th2x=3+2=5

d)x-3=+-8

th1x=-8+3=-5

th2x=8+3=11

e)x+1=(72-9):3=+-21

th1x=-21-1=-22

th2x=21-1=20

j)lxl=(17-45):43=-28/43

=>x\(\in\Phi\)

x-1=(7+5):3=+-4

th1x=-4+1=-3

th2x=4+1=5

mk làm tắt đó tự suy luận ra mk làm

xong rồi nha 

1. x + (-7) = -20 

=> x = -20 - (-7) 

=> x = -20 + 7 

=> x = -13

Vậy x = -13 

2. x + (-15) = 5 

=> x = 5 - (-15) 

=> x = 5 + 15 

=> x = 20 

3. (-95) + x = 10 

=> x = 10 - (-95) 

=> x = 10 + 95 

=> x = 105 

4. 8+ x = 12 

=> x = 12 - 8 

=> x = 4 

5. x + (-45) = -62 + 17 

=> x + (-45) = -45

=> x = -45 - (-45) 

=> x = -45 + 45 

=> x = 0 

6 . x + 29 = |-43|  + (-43) 

=> x + 29 = 43 + (-43) 

=> x + 29 = 0 

=> x = 0 - 29 

=> x = -29 

7 . 43 + (9 - 21) = 317 - (x + 317) 

=> 43 + (-12) = 317 - x - 317 

=> 31  = 317 - x - 317 

=> 317 - x - 317 = 31 

=> 317 - x = 31 + 317 

=> 317 - x = 348

=> x = 317 - 348 

=> x = -31 

Mỏi tay quá , bn tự làm nốt nha :)

tìm x thuộc Z

x+(-7)=-20

x=(-15)=5

(-95)+x=10

8+x=-12

x+(-45)=-62+17

x+29=|-43|+(-43)

43+(9-21)=317-(x+317)

|x|+|-4|=7

|x-1|+(-3)=17

a)=20

b)=-1

c)=-1 hoặc 5

d)=-17 hoặc 23

e)=20 hoặc=-22

i)=71 hoặc -71

=5 hoặc -3

Bạn ơi bạn có thể làm hết ra có đc ko bạn

a) x=15-(-5)

x=20

b)2x+17=15

2x=15-17

2x=-2

x=-2/2=-1

c)=>x-2=3

x=3+2=5

hoặc x-2=-3

x=-3+2=-1

d)|x-3|=13+7=20

=>x-3=20

x=20+3=23

hoặc x-3=-20

x=-20+3=-17

còn lại tự giải nhé

a) x.  -5/3 = 1

=> x     = 1 : -5/3

=> x     = -3/5

b) x : 17/8 = (-2). -9/17

    => x : 17/8 = 18/17

    => x            = 18/17 . 17/8

    => x            = 9/4

c) x . 1/5 . 7/10 = 1

=> x . 7/50 = 1

=> x           = 1 : 7/50

=> x           = 50/7

Chúc bạn học tốt 

a) \(x=1:\frac{-5}{3}=\frac{1.-3}{5}=\frac{-3}{5}\)

b) \(x:\frac{17}{8}=-2.\frac{-9}{17}=\frac{18}{17}\)

\(x=\frac{18}{17}.\frac{17}{8}=\frac{18}{8}=\frac{9}{4}\)

c) \(x=1:\frac{7}{10}:\frac{1}{5}=1.\frac{10}{7}.5=5.\frac{10}{7}=\frac{50}{7}\)

Chúc bạn học tốt!!!

a) 

(1/3-1/5)x1/4 = 1/3x1/4-1/5x1/4=1/12-1/20=1/30

(1/3-1/5)x1/4 = 2/15x1/4=1/30

b)

2/5 x 3/7 + 2/5 x 4/7= 6/35 + 8/35 = 14/35 = 2/5

2/5 x 3/7 + 2/5 x 4/7= (3/7+4/7) x 2/5 = 1 x 2/5 = 2/5

a: C1: (1/3-1/5)*1/4

=2/15*1/4=2/60=1/30

C2: (1/3-1/5)*1/4

=1/3*1/4-1/5*1/4

=1/12-1/20=1/30

b: C1: 2/5*3/7+2/5*4/7

=6/35+8/35=14/35=2/5

C2: 2/5*3/7+2/5*4/7

=2/5(3/7+4/7)

=2/5*1=2/5

a) \(\dfrac{13}{20}+\dfrac{3}{5}+x=\dfrac{5}{6}\)

\(\Rightarrow\dfrac{5}{4}+x=\dfrac{5}{6}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{5}{4}\)

\(\Rightarrow x=\dfrac{-5}{12}\)

b) \(x+\dfrac{1}{3}=\dfrac{2}{5}-\dfrac{-1}{3}\)

\(\Rightarrow x+\dfrac{1}{3}=\dfrac{11}{15}\)

\(\Rightarrow x=\dfrac{11}{15}-\dfrac{1}{3}\)

\(\Rightarrow x=\dfrac{2}{5}\)

c)\(\dfrac{-5}{8}-x=\dfrac{-3}{20}-\dfrac{-1}{6}\)

\(\dfrac{-5}{8}-x=\dfrac{1}{60}\)

\(\Rightarrow x=\dfrac{-5}{8}-\dfrac{1}{60}\)

\(\Rightarrow x=\dfrac{-77}{120}\)

d) \(\dfrac{3}{5}-x=\dfrac{1}{4}+\dfrac{7}{10}\)

\(\Rightarrow\dfrac{3}{5}-x=\dfrac{19}{20}\)

\(\Rightarrow x=\dfrac{3}{5}-\dfrac{19}{20}\)

\(\Rightarrow x=\dfrac{-7}{20}\)

e) \(\dfrac{-3}{7}-x=\dfrac{4}{5}+\dfrac{-2}{3}\)

\(\Rightarrow\dfrac{-3}{7}-x=\dfrac{2}{15}\)

\(\Rightarrow x=\dfrac{-3}{7}-\dfrac{2}{15}\)

\(\Rightarrow x=\dfrac{-59}{105}\)

g) \(\dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)

\(\Rightarrow\dfrac{-5}{6}-x=\dfrac{1}{4}\)

\(\Rightarrow x=\dfrac{-5}{6}-\dfrac{1}{4}\)

\(\Rightarrow x=\dfrac{-13}{12}\)