a) 2x=138+72\(\Leftrightarrow\)2x=210\(\Rightarrow\)x=105

b) 237-x=103\(\Rightarrow\)x=237-103=134

c) 6x+8=50\(\Leftrightarrow\)6x=50-8=42\(\Rightarrow\)x=42:6=7

123-5.(x+4)=38

 5(x+4)=123-38

 5(x+4)=85

 x+4=85:5

 x+4=17

 x=17-4

 x=13

10+2x=2.(3²-1)

 10+2x=2.(9-1)

 10+2x=2.8

 2x=16-10

2x=6

 x=6:2

 x=3

2.x-138=2³.3²

 2.x-138=72

 2.x=72+138

 2.x=210

 x=210:2

 x=105

[102+(28-2x)]:20-5=1

 (102+28-2x):20=6

 130-2x=120

 2x=130-120

 2x=10

 x=10:2

 x=5

231-(x-6)=1339:13

 231-(x-6)=103

 x-6=231-103

 x-6=128

 x=128+6

 x=134

123-5.(x+4)=38

5.(x+4)=123-38

5.(x+4)=85

(x+4)=85/5

x+4=17

x=17-4

x=13

10 + 2x = 2(3² - 1)

=> 10 + 2x = 2(9 - 1)

=> 10 + 2x = 2.8

=> 10 + 2x = 16

=> 2x = 16 - 10

=> 2x = 6

=> x = 6/2

=> x = 3

a)13-2(x+1)=7

  2.(x+1)=13-7

  2.(x+1)=6

  x+1=6/2

  x+1=3 

  x=3-1

  x=2

a, 13 - 2 ( x + 1 ) = 7

          2 .( x + 1 ) = 13 - 7
          2 .( x + 1 ) = 6
                x + 1   = 6 : 2
                x + 1    = 3
                x          = 3 - 1
                x           = 4

b)6x+2.4=5².2

6x+2=50

6x=48

x=8

c)420+65.4=(x+175):5+30

(x+175):5+30=680

(x+175):5=650

x+175=3250

x=3075

\(a.2.x-138=2^3.3^2\)

    \(2.x-138=8.9\)

    \(2.x-138=72\)

    \(2.x\)          \(=72+138\)

    \(2.x\)          \(=210\)  

       \(x\)           \(=210:2\)  

       \(x\)            \(=105\)

\(b.231-\left(x-6\right)=1339:13\)

    \(231-\left(x-6\right)=103\)

                    \(x-6=231-103\)

                    \(x-6=128\)

                    \(x\)      \(=128+6\) 

                    \(x\)       \(=134\)

\(c.\left[\left(6.x-72\right):2-84\right].28=5628\)

    \(\left[\left(6.x-72\right):2-84\right]\)   \(=5628:28\)

       \(\left(6.x-72\right):2-84\)      \(=201\)

          \(\left(6.x-72\right):2\)               \(=201-84\)

           \(\left(6.x-72\right):2\)              \(=117\)

              \(6.x-72\)                      \(=117.2\)

               \(6.x-72\)                      \(=234\)

               \(6.x\)                                  \(=234+72\)   

               \(6.x\)                                   \(=306\)    

                   \(x\)                                     \(=306:6\)

                  \(x\)                                       \(=51\)

mik nè

Cam on nha

\(a)(2367-x)-1017=205\)

 \(\Leftrightarrow(2367-x)=205+1017\)

\(\Leftrightarrow(2367-x)=1222\)

\(\Leftrightarrow x=2367-1222\)

\(\Leftrightarrow x=1145\)

\(b)(6x-39):3\cdot28=5628\)

\(\Leftrightarrow(6x-39):3=\frac{5628}{28}\)

\(\Leftrightarrow(6x-39):3=201\)

\(\Leftrightarrow(6x-39)=201\cdot3\)

\(\Leftrightarrow(6x-39)=603\)

\(\Leftrightarrow6x=603+39\)

\(\Leftrightarrow6x=642\)

\(c)5x-x+2x=42\)

\(\Rightarrow5x-1x+2x=42\)

\(\Rightarrow6x=42\)

\(\Rightarrow x=7\)

d\()\)Tương tự câu a và b

e\()(x-2)(x-3)=0\)

Xét có hai trường hợp :

TH1 : x - 2 = 0    => x = 2

TH2 : x - 3 = 0    => x = 3

Vậy : \(\hept{\begin{cases}x=2\\x=3\end{cases}}\)

\(\Leftrightarrow x=\frac{642}{6}=107\)

c) 10 + 2x = 2(3² - 1)

10 + 2x = 16

2x = 6

x = 3

d) 2x - 138 = 2³.3²

2x - 138 = 72

2x = 72 + 138

2x = 210

x = 210/2 = 105

a) 1032 : (x : 4) = 6

x : 4 = 1032 : 6 = 172

X = 172 x 4 = 688

b) 123 - 5(x + 4) = 38

5(x +  4) = 123 - 38 = 85

x + 4 = 85/5 = 17

x = 17 - 4 = 13

f.x=134

g.x=5 ;x=-1 

h. x=388 ; x=-78

a) \(2x-13=2^3.3^2\)

=> \(2x-13=8.9=27\)

=> \(2x=27-13=14\)

=> \(x=7\)

b) \(231-\left(x-6\right)=1339:13=103\)

=> \(x-6=231-103=128\)

=> \(x=6+218=224\)

Tíc nha!

a) \(6-2\left(x+4\right)=-4\)

\(\Leftrightarrow6-2x-8=-4\)

\(\Leftrightarrow-2-2x=-4\)

\(\Leftrightarrow-2x=-4+2\)

\(\Leftrightarrow-2x=-2\)

\(\Leftrightarrow x=1\)

Vậy \(x=1\)

b) tự làm.

c) \(2x-15:5=-7\)

\(\Leftrightarrow2x-7,5=-7\)

\(\Leftrightarrow2x=-7+7,5\)

\(\Leftrightarrow2x=0,5\)

\(\Leftrightarrow x=0,25\)

\(\Leftrightarrow x=\dfrac{1}{4}\)

Vậy \(x=\dfrac{1}{4}\)

d) \(231-\left(x-6\right)=1339:13\)

\(\Leftrightarrow231-x+6=103\)

\(\Leftrightarrow237-x=103\)

\(\Leftrightarrow237-x+6=103\)

\(\Leftrightarrow-x=103-237\)

\(\Leftrightarrow-x=-134\)

\(\Leftrightarrow x=134\)

e) đề j mà có 2 dấu bằng >> sai :v

f) \(28-x^3=1\)

\(\Leftrightarrow-x^3=1-28\)

\(\Leftrightarrow-x^3=-27\)

\(\Leftrightarrow x^3=27\)

\(\Leftrightarrow x^3=3^3\)

\(\Leftrightarrow x=3\)

Vậy \(x=3\)

g) \(\left(x+2\right)^3=27\)

\(\Leftrightarrow\left(x+2\right)^3=3^3\)

\(\Leftrightarrow x+2=3\)

\(\Leftrightarrow x=3-2\)

\(\Leftrightarrow x=1\)

Vậy \(x=1\)

h) \(81-\left(x-5\right)^2=56\)

\(\Leftrightarrow-\left(x-5\right)^2=56-81\)

\(\Leftrightarrow-\left(x-5\right)^2=-25\)

\(\Leftrightarrow\left(x-5\right)^2=25\)

\(\Leftrightarrow x-5=\pm5\)

\(\Leftrightarrow\left[{}\begin{matrix}x-5=5\\x-5=-5\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=5+5\\x=-5+5\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=10\\x=0\end{matrix}\right.\)

Vậy \(x_1=0;x_2=10\)

j) \(x^2=9\)

\(\Leftrightarrow x=\pm3\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)

Vậy \(x_1=-3;x_2=3\)

l) tự làm.

bn ơi chỗ 4 mũ 5 là nhân à