a. \(2x-138=2^3.3^2\\ \Leftrightarrow2x-138=72\\ \Leftrightarrow2x=210\\ \Leftrightarrow x=105\)

b. \(231-\left(x-6\right)=1339:13\\ \Leftrightarrow231-\left(x-6\right)=103\\ \Leftrightarrow x-6=128\\ \Leftrightarrow x=134\)

x=105

x*6,5+x*3,5=20

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

Vậy x=105

k mk nha

2x - 138 = 2³.3²

2x - 138 = 8.9

2x - 138 = 72

2x = 72 + 138

2x = 210

x = 210 : 2

x = 105

Answer : 105

2.x-138=72

2x=138+72

2x=210

x=105

2.x-138=8.9

2.x-138=72

2.x=72+138

2.x=210

x=210:2

x=105

k cho mình nha

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

\(=>2x-138=72\)

\(=>2x=72+138\)

\(=>2x=210\)

\(=>x=\frac{210}{2}\)

\(=>x=105\)

2.x -138 = 8.9
2.x -138= 72
2.x= 72+138
2.x=210
x=210: 2
x=105
 

Lời giải:

a. $121-3(x-5)=6$

$3(x-5)=121-6=115$

$x-5=115:3=\frac{115}{3}$

$x=\frac{115}{3}+5=\frac{130}{3}$

b.

$2x-138=2^3.3^2=72$

$2x=72+138=210$

$x=210:2=105$

c.

$x-3\vdots 7$

$\Rightarrow x-3\in\left\{0;7;14;21;28;35;42;49; 56;...\right\}$

Mà $10< x< 50$ nên $x\in\left\{14;21;28;35;42;49\right\}$

d.

$27\vdots x+1$

$\Rightarrow x+1\in\left\{\pm 1; \pm 3; \pm 9; \pm 27\right\}$

$\Rightarrow x\in\left\{0; -2; -4; 2; 8; -10; 26; -28\right\}$

a ) 121-3.(x - 5 ) = 6

3.(x-5) = 121 -6

3. (x-5)=115

x-5  = 115:3

x-5=35

x=35+5

x = 40

b) 2x - 138 = 2'3. 3'2

2x -138=8.9

2x-138=72

2x=72+138

2x=210

x=210:2

x=105

c) theo bài ra : x-3 ∈ B(7)

ta có B(7)=(0,7,14,21,28,35,49,56,...)

=) x-3 ∈ ( 0,7,14,21,28,35,49,56,...)

=) x ∈( 3 , 10,17,24,31,38,42,58,..)

mà 10 <x<50 nên x ∈ ( 17 , 24 ,31,38,42 )

vậy x ∈(17,24,31,38,42)

Lời giải:

a. $121-3(x-5)=6$

$3(x-5)=121-6=115$

x-5=115:3=\frac{115}{3}x−5=115:3=3115​

x=\frac{115}{3}+5=\frac{130}{3}x=3115​+5=3130​

b.

2x-138=2^3.3^2=722x−138=23.32=72

$2x=72+138=210$

$x=210:2=105$

c.

$x-3⋮7$

$\Rightarrow x-3\in \left\{0;7;14;21;28;35;42;49;56;...\right\}$

Mà $10<x<50$ nên $x\in \left\{14;21;28;35;42;49\right\}$

d.

$27⋮x+1$

$\Rightarrow x+1\in \left\{\pm 1;\pm 3;\pm 9;\pm 27\right\}$

$\Rightarrow x\in \left\{0;-2;-4;2;8;-10;26;-28\right\}$

2.x-138=2³.3²

2.x-138=8.9

2.x-138=72

2.x=72+138

2.x=210

x=210:2

x=105

2.x-138=2³.3²

=>2x-138=8.9

=>2x-138=72

=>2x=72+138

=>2x=210

=>x=210:2

=>x=105

\(2.x-138=2^3.3^2\)
\(\Rightarrow2.x-138=8.9\)
\(2.x=72\)
\(\Rightarrow2.x=72+138\)
\(2.x=210\)
\(\Rightarrow x=210\div2\)
\(\Rightarrow x=105\)

2.x-138=72

2.x=72+138

2.x=210

x=105

2.x -138 = 2³.3²

=> 2.x - 138 = 8.9 = 72 

=> 2.x = 72 + 138 = 210

=> x = 210 : 2

=> x = 105 

\(2\times x-138=2^3\times3^2\)

\(2\times x-138=72\)

              \(2\times x=72+138\)

               \(2\times x=210\)

                        \(x=210:2\)

                        \(x=105\)

2 * x - 138 = 2³ * 3²

2 * x - 138 = 8 * 9

2 * x - 138 = 72

     x - 138 = 72 : 2

     x - 138 = 36

     x         = 36 + 138

     x         = 174