a) \(2^x\cdot4=128\)

\(\Rightarrow2^x\cdot2^2=2^7\)

\(\Rightarrow2^{x+2}=2^7\)

\(\Rightarrow x+2=7\)

\(\Rightarrow x=5\)

b) \(\left(2x+1\right)^3=125\)

\(\Rightarrow\left(2x+1\right)^3=5^3\)

\(\Rightarrow2x+1=5\)

\(\Rightarrow2x=4\)

\(\Rightarrow x=4:2\)

\(\Rightarrow x=2\)

c) \(2x-2^6=6\)

\(\Rightarrow2x-64=6\)

\(\Rightarrow2x=70\)

\(\Rightarrow x=70:2\)

\(\Rightarrow x=35\)

d) \(64\cdot4^x=45\)

\(\Rightarrow4^3\cdot4^x=45\)

\(\Rightarrow4^{x+3}=45\)

Xem lại đề

e) \(27\cdot3^x=243\)

\(\Rightarrow3^3\cdot3^x=3^5\)

\(\Rightarrow3^{x+3}=3^5\)

\(\Rightarrow x+3=5\)

\(\Rightarrow x=2\)

g) \(49\cdot7^x=2401\)

\(\Rightarrow7^2\cdot7^x=7^4\)

\(\Rightarrow7^{x+2}=7^4\)

\(\Rightarrow x+2=4\)

\(\Rightarrow x=2\)

h) \(3^x=81\)

\(\Rightarrow3^x=3^4\)

\(\Rightarrow x=4\)

k) \(3^4\cdot3^x=3^7\)

\(\Rightarrow3^{x+4}=3^7\)

\(\Rightarrow x+4=7\)

\(\Rightarrow x=3\)

n) \(3^x+25=26\cdot2^2+2\cdot3^0\)

\(\Rightarrow3^x+25=104+2\)

\(\Rightarrow3^x+25=106\)

\(\Rightarrow3^x=81\)

\(\Rightarrow3^x=3^4\)

\(x=4\)

`@` `\text {Ans}`

`\downarrow`

`a)`

`2^x*4 = 128`

`=> 2^x = 128 \div 4`

`=> 2^x = 2^7 \div 2^2`

`=> 2^x = 2^5`

`=> x = 5`

Vậy, `x = 5.`

`b)`

\(\left(2x+1\right)^3=125\)

`=> (2x + 1)^3 = 5^3`

`=> 2x + 1 = 5`

`=> 2x = 5-1`

`=> 2x = 4`

`=> x = 4 \div 2`

`=> x = 2`

Vậy, `x = 2`

`c)`

\(2x-2^6=6\)

`=> 2x = 6+2^6`

`=> 2x = 70`

`=> x = 70 \div 2`

`=> x = 35`

Vậy, `x = 35`

`d)`

\(64\cdot4^x=45\) Bạn xem lại đề

`e)`

`27*3^x = 243`

`=> 3^3 * 3^x = 3^5`

`=> 3^(3 + x) = 3^5`

`=> 3 + x = 5`

`=> x = 5 - 3`

`=> x = 2`

Vậy, `x = 2`

`g)`

`49* 7^x = 2401`

`=> 7^2 * 7^x = 7^4`

`=> 7^(2 + x) = 7^4`

`=> 2 + x = 4`

`=> x = 4 - 2`

`=> x = 2`

Vậy, `x = 2`

`h)`

`3^x = 81`

`=> 3^x = 3^4`

`=> x = 4`

Vậy, `x = 4`

`k)`

`3^4 * 3^x = 3^7`

`=> 3^(4 + x) = 3^7`

`=> 4 + x = 7`

`=> x = 7 - 4`

`=> x = 3`

Vậy, `x = 3`

`n)`

`3^x + 25 = 26*2^2 + 2*3^0`

`=> 3^x + 25 = 104 + 2`

`=> 3^x + 25 = 106`

`=> 3^x = 106 - 25`

`=> 3^x = 81`

`=> 3^x = 3^4`

`=> x = 4`

Vậy, `x = 4.`

\(#48Cd\)

(2x + 1)³ = 343

=> (2x + 1)³ = 7³

=> 2x + 1 = 7

=> 2x = 7 - 1

=> 2x = 6

=> x = 6 : 2

=> x = 3

3^x + 25 = 26 . 2² = 2 . 30

=> 3^x + 25 = 26 . 4

=> 3^x + 25 = 104

=> 3^x = 104 - 25

=> 3^x = 79

x = ...

=.= đề sai rồi

anh chả hiểu

dái wa      

Giúp mình đi mình đang cần gấp

`a) 27.3^x =243`

`3^x=243/27=9`

`3^x=3^2`

`=>x=2`

`b) 49.7^x =2401`

`7^x = 2401/49=49`

`7^x=7^2`

`=>x=2`

`c) 3^x +25 =26*2^2+2.3^0`

`3^x = 26.4+2.1-25 = 81`

`3^x =3^4`

`=>x=4`

\(e,27.3^x=243\\ \Leftrightarrow3^3.3^x=3^5\\ \Leftrightarrow3^{3+x}=3^5\\ \Rightarrow3+x=5\\ \Leftrightarrow x=2\\ g,49.7^x=2401\\ \Leftrightarrow7^2.7^x=7^4\\ \Leftrightarrow7^{2+x}=7^4\\ \Rightarrow2+x=4\\ \Leftrightarrow x=2\\ h,3^x+25=26.2^2+2.3^0\\ \Leftrightarrow3^x+25=26.4+2.1\\ \Leftrightarrow3^x=104+2-25\\ \Leftrightarrow3^x=81=3^4\\ Vậy:x=4\)

b1

A=(125+2)² - (125-2)² = 127² - 123² = 1000

a) = 1000

tíck mik nha

a ) 126 - 2x = 12 - ( -28 )

     126 - 2x = 40

     2x = 126 - 40

     2x = 86 

     x = 86 : 2

     x = 43

b ) 25 - 5( x + 1 ) = 30 - 125

     25 - ( 5x + 5 ) = -95

     25 - 5x - 5 = -95

     20 - 5x = -95

     5x = 20 - ( - 95 )

     5x = 115

     x = 115 : 5

     x = 23

c ) I 3x - 1 I - 25 = 73 

     I 3x - 1 I = 73 + 25

     I 3x - 1 I = 98

=> 3x - 1 = 98 hoặc 3x - 1 = -98

=> 3x = 98 + 1 hoặc 3x = -98 + 1

=> 3x = 99 hoặc 3x = -97

=> x = 99 : 3 hoặc x = -97 : 3 

=> x = 33 hoặc x = -93/3

d ) 2( x + 2 ) - 6 = 120 - 4x 

     2x + 4 - 6 = 120 - 4x 

     2x - 2 = 120 - 4x

     2x + 4x = 120 + 2

     6x = 122

     x = 122 : 6

     x = 61/3

a) x = 43

b) x = 23

c) x = 33 hoac x= -97/3

a) (125 - x) + 25 = 98

125 - x = 98 - 25

125 - x = 73

x = 125 - 73

x = 52

b) 100 : (x + 20) = 68 : 34

100 : (x + 20) = 2

x + 20 = 100 : 2

x + 20 = 50

x = 50 - 20

x = 30

c) (3x + 12) . 5 = 25 . 4 - 10

(3x + 12) . 5 = 100 - 10

(3x + 12) . 5 = 90

3x + 12 = 90 : 5

3x + 12 = 18

3x = 18 - 12

3x = 6

x = 6 : 2

x = 3

d) 210 : (2x - 3) - 20 = 10

210 : (2x - 3) = 10 + 20

210 : (2x - 3) = 30

2x - 3 = 210 : 30

2x - 3 = 70

2x = 70 + 3

2x = 73

x = 73/2

a, ( 125 - x ) + 25 = 98

⇒ 125 - x = 73

⇒ x = 52.

Vậy..

b, 100 : ( x + 20 ) = 68 : 34

⇒ 100 : ( x + 20 ) = 2

⇒ x + 20 = 50

⇒ x = 30

Vậy...

c, ( 3 . x + 12 ) . 5 = 25 . 4 - 10

⇒ ( 3 . x + 12 ) . 5 = 90

⇒ 3 .x + 12 = 18

⇒ 3x = 6

⇒ x = 2.

Vậy...

d, 210 : ( 2 .x - 3 ) - 20 = 10

⇒ ( 2 .x - 3 ) - 20 = 21

⇒ 2x - 3 = 41

⇒ 2x = 44

⇒ x = 22.

Vậy..