3|x| = 18 ⇒ |x| = 18 : 3 = 6 ⇒ x = 6 hoặc x = –6

      \(\left(x-3\right)-3.\left(x-5\right)=4.\left(3-x\right)-18\)
\(\Leftrightarrow x-3-3x+15=12-4x-18\)
\(\Leftrightarrow-2x+12=-4x-6\)
\(\Leftrightarrow-2x+4x=-6-12\)
\(\Leftrightarrow2x=-18\)
\(\Leftrightarrow x=-9\)

Ư(15)= {-1;-3;-5;-15;1;3;5;15}

ước nguyên âm nhỏ nhất của 15 là -15 

=> x+3=-15

<>x=-18

ê làm sao có thẻ 100k

\(\frac{x}{9}-\frac{3}{y}=\frac{1}{18}\)

\(\frac{x}{9}-\frac{1}{18}=\frac{3}{y}\)

\(\frac{2x}{18}-\frac{1}{18}=\frac{3}{y}\)

\(\frac{2x-1}{18}=\frac{3}{y}\)

\(\left(2x-1\right)y=18.3=54\)

=> 2x - 1 ; y \(\in\)Ư(54) ={...}

Làm nốt e nhé, chăm chỉ lên ! 

a)   x + 118 = 218

x = 218 – 118

x = 100

b)   18 – x = -17

X = 18 – (-17)

X = 35

c)    (-18) – x = -17

X = (-18) – (-17)

X = -1

d)124 + (118 – x) = 217

118 – x = 93

X = 118 – 93

X = 25

e) (3x – 6).3 = 3⁴

(3x – 6).3 = 81

3x – 6 = 27

3x = 33

ð X = 11

g) 23.(42 – x) = 46

42 – x = 2

ð X = 40

h) 84 – (3x + 8) = 34

3x + 8 = 84 – 34

3x + 8 = 50

3x = 50 – 8

3x = 42

X = 42 : 3

ð X = 14

i)               3.(2x + 1) – 19 = 14

3.(2x + 1) = 14 + 19

3.(2x + 1) = 33

2x + 1 = 33 : 3

2x + 1 = 11

2x = 11 – 1

2x = 10

X = 10 : 2

ð X = 5

k) 6x – 302 = 2³.5

6x – 302 = 40

6x = 40 + 302

6x = 342

X = 342 : 6

ð X = 57

m) (x – 1)² = 81

(x – 1)² = 9²

ð X – 1 = 9

ð X = 9 + 1

ð X = 10

n) 2^x+1 – 5 = 27

2^x+1 = 27 + 5

2^x+1 = 32

2^x+1 = 2⁵

ð X = 4

a) \(x+118=218\)

    \(x=218-118\)

    \(x=100\) 

b)\(18-x=-17\)

   \(-x=-18-17\)

    \(-x=-35\)

     \(x=35\)

c)\(\left(-18\right)-x=-17\)

     \(-x=18-17\)

     \(-x=1\)

      \(x=-1\)

d)\(124+\left(118-x\right)=217\)

    \(118-x=217-124\)

     \(118-x=93\)

     \(x=25\)

e) \(\left(3x-6\right).3=3^4\)

     \(3x-6=3^3\)

     \(3x-6=27\)

     \(x=11\)

g)\(23.\left(42-x\right)=46\)

    \(42-x=2\)

     \(x=40\)

h) \(84-\left(3x+8\right)=34\)

    \(3x+8=50\)

     \(x=14\)

 i)  \(3\left(2x+1\right)-19=14\)

      \(3\left(2x+1\right)=33\)

       \(2x+1=11\)  

        \(x=5\)

k) \(6x-302=2^3.5\)

    \(6x-302=8.5\)

    \(x=57\)

m) \(\left(x-1\right)^2=81\)

      \(\left(x-1\right)^2=9^2\)

       \(x-1=9\)

       \(x=10\)

n) \(2^{x+1}-5=27\)

    \(2^{x+1}=32\)

    \(2^{x+1}=2^5\)

   \(x+1=5\)  

     \(x=4\)

m) \(2^x+2^{x+1}+2^{x+2}=56\)

    \(2^x.1+2^x.2+2^x.2^2=56\)

    \(2^x\left(1+2+4\right)=56\)

     \(2^x=8\)

    \(2^x=2^3\)

     \(x=3\)

   \(2^x=8\)

a: =>-12<x<2y<-9

=>x=-11; y=-5

b: =>-7<3(x-1)<8

\(\Leftrightarrow3\left(x-1\right)\in\left\{-6;-3;0;3;6\right\}\)

\(\Leftrightarrow x-1\in\left\{2;1;0;-1;-2\right\}\)

hay \(x\in\left\{3;2;1;0;-1\right\}\)