a.70 -5.(x-3)=45

x-3=70-5-45

x-3=20

x=20-3=17

b.2x-138=8.9

2x-138=72

2x=72+138

2x=210

x=210:2=105

c.10+2n=16

2n=16-10

2n=6

n=6:3=2

d.[(4x+28).3+55]:5=35

[(4x+28).3+55]=35x5=175

4x+28=(175-55):3

4x+28=40

4x=40-28=12

x=12:4=3

Dung thi k mk nha

Chuc bn hoc gioi nha

\(2x-138=8\cdot9\)

\(\Leftrightarrow2x-138=72\)

\(\Leftrightarrow2x=72+138\)

\(\Leftrightarrow2x=210\)

\(\Leftrightarrow x=210:2=105\)

Vậy x = 105

    2.x - 138 = 8.9

=>2.x - 138 = 72  

=> 2.x         = 72 + 138

=> 2.x         = 210

=>  x           = 210 : 2

=> x            = 105

trl:

      2x - 138 = 8.9

=> 2x - 138 = 72

=>         2x = 72+138

=>           2x=210

=>             x=210 : 2

=>             x = 105.

a) 42 - x = 5

x = 42 - 5

x = 37

b) 15.(x + 4) = 75

x + 4 = 75 : 15

x + 4 = 5

x = 5 - 4

x = 1

d) x + 18 = 12

x = 12 - 18

x = -6

e) 2x - 15 = -19

2x = (-19) + 15

2x = -4

x = -4 : 2

x = -2

f) 36 : (x^3 - 12) = -3

x^3 - 12 = 36 : (-3)

x^3 - 12 = -12

x^3 = 0

=> x = 0

g)x + 15 = 35

x = 35 - 15

x = 20

h) 2x - 13 = 3^2

2x - 13 = 9

2x = 9 + 13

2x = 22

x = 22 : 2

x = 11

a) 42-x=5

         x=42-5

         x= 37

b)15*(x+4)=75

        x+4=75:15

        x+4=5

        x    =5-4

       x     = 1

a) 42 - x = 5

x = 42 - 5

x = 37

b) 15.(x + 4) = 75

x + 4 = 75 : 15

x + 4 = 5

x = 5 - 4

x = 1

d) x + 18 = 12

x = 12 - 18

x = -6

e) 2x - 15 = -19

2x = (-19) + 15

2x = -4

x = -4 : 2

x = -2

f) 36 : (x^3 - 12) = -3

x^3 - 12 = 36 : (-3)

x^3 - 12 = -12

x^3 = 0

=> x = 0

g)x + 15 = 35

x = 35 - 15

x = 20

h) 2x - 13 = 3^2

2x - 13 = 9

2x = 9 + 13

2x = 22

x = 22 : 2

x = 11

x=`105

2x-138=72

2x=72+138

2x=110

  x=110:2

  x=55

vậy x=55

2x - 138 = 72

=> 2x = 72 + 138 

=> 2x = 210

=> 2x = 210

=> x = 210 : 2

=> x = 105

2x+138=276

       2x=276-138

       2x=138

       x=138:2

       x=69

bn chọn đáp án của mk nha ^_^

2x + 138 = 276

2x = 276 - 138

2x = 138

x = 138 : 2

x = 69

Answer : 69

2x +138 = 276

2x         = 276-138

2x         = 138

x           = 138:2

x          = 69

k mk nha pạn!

cảm ơn trước

2x-138=72

=>2x=72+138

=>2x=210

=>x=210:2

=>x=105

d)2x-138=2².3²

⇔2x=36+138

⇔ x = 87 

2x - 138 = 36

2x           = 36 + 138

2x           =  174

  x           =   174 : 2

   x          =    87

Vậy x = 87

2x-138=2².3²

2x-138=4.9

2x-138=36

2x=36+138

2x=174

x=87

\(72-x=50\\ \Rightarrow x=22\)

\(2x-138=72\\ \Rightarrow2x=210\\ \Rightarrow x=105\)

\(5.3^x=135\\ \Rightarrow3^x=27\\ \Rightarrow3^x=3^3\\ \Rightarrow x=3\)