a: =>2x+10=4^2=16

=>2x=6

=>x=3

b: =>2x-138=8*9=72

=>2x=138+72=210

=>x=105

c: =>231-(x-6)=103

=>x-6=128

=>x=134

\(a.10+2x=4^5:4^3\\ \Leftrightarrow10+2x=4^2\\ \Leftrightarrow2x=6\\ \Leftrightarrow x=3\)

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

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

Chú ý : Nếu bạn chưa học \(\Leftrightarrow\)  thì bạn bỏ đi nha !

a: Ta có: \(814-\left(x-305\right)=712\)

\(\Leftrightarrow x-305=102\)

hay x=407

b: Ta có: \(2x-138=2^3\cdot2^2\)

\(\Leftrightarrow2x=32+138=170\)

hay x=85

c: Ta có: \(20-\left[7\left(x-3\right)+4\right]=2\)

\(\Leftrightarrow7\left(x-3\right)+4=18\)

\(\Leftrightarrow7\left(x-3\right)=14\)

\(\Leftrightarrow x-3=2\)

hay x=5

2.x – 138 = 23.32

2x – 138 = 8.9

2x – 138 = 72

2x = 72 + 138

2x = 210

x = 210 : 2

x = 105

Vậy x = 105

b) 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

c) 2.x - 138 = 23.32
=>2.x - 138 = 736
=>2.x          = 736 + 138
=>2.x          =     874
=>   x          = 874 : 2
=>   x          =    437

d) 70 - 5.(x-3) = 45
=>       5.(x-3) = 70 - 45
=>       5.(x-3) =     25
=>          (x-3) = 25 : 5
=>           x-3  =      5
=>           x     = 5 + 3
=>           x     =    8

g: =>3x-10=200

hay x=70

c) (7x + x – 28) :100 – 38 = 9

<=> 8x - 28 = 4700

<=> x = 591

d) 936 – (4x + 5x ) = 900

<=> 9x = 36

<=> x = 4

a) x+3=12

x=12-3

x=9

b)(x-3):2=5¹⁴:5¹²

=>(x-3):2=5²

=>(x-3):2=25

=>x-3=25.2

=>x-3=50

=>x=50+3

=>x=53

c)4x+3x=30-20:10

=>x(4+3)=30-2

=>7x=28

=>x=28:7

=>x=4

d)2x-138=2³.3²

=>2x-138=8.9

=>2x-138=72

=>2x=72+138

=>2x=210

=>x=210:2

=>x=105

a) x + 3 = 12

x = 12 - 3

x = 9

b) ( x - 3 ) : 2 = 5¹⁴ : 5¹²

( x - 3 ) : 2 = 5^14-12

( x - 3 ) : 2 = 5²

( x - 3 ) : 2 = 25

x - 3 = 50

x = 53

c) 4x + 3x = 30 - 20 : 10

7x = 28

x = 4

d) 2x - 138 = 2³ x 3²

2x - 138 = 8 x 9

2x - 138 = 72

2x = 210

x = 105

a: \(3^2+10:2=9+5=14\)

b: \(13\cdot\left(23+17\right)-17\cdot\left(23+13\right)\)

\(=13\cdot23+13\cdot17-17\cdot23-17\cdot13\)

\(=13\cdot23-17\cdot23\)

\(=-4\cdot23=-92\)

c: \(-8+2\left(x-4\right)=2^3\cdot3^2\)

=>\(2\left(x-4\right)-8=8\cdot9=72\)

=>2(x-4)=72+8=80

=>x-4=40

=>x=44

bn ơi trên là 3² và 2³ hay 32 và 23?

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.

$27⋮x+1$

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

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

a: =>25-4x=1

=>4x=24

hay x=6

b: =>2x-4=0

hay x=2

c: =>x-35=115

hay x=150

d: =>x-2=12

hay x=14

e: =>x-36=216

hay x=252