a)5^x=125=5³

=>x=3

b)3^2x=81=3⁴

=>2x=4

x=4/2

x=2

c)5^2x-3-2*5²=5²*3

5^2x-3=5²*3+2*5²=5²(3+2)=5²*5

5^2x-3=5³

=>2x-3=3

2x=3+3

2x=6

x=6/2

x=3

lần sau nếu ghi dẫu mũ như vậy thì bạn nhớ ngoặc vào 

chịu mới lớp 4 mà !!!

hỏi làm chi

a) 5^x = 125

\(\Rightarrow\)5^x = 5³

\(\Rightarrow\)x = 3

b, 3^2x = 81

\(\Rightarrow\)3^2x = 3⁴

\(\Rightarrow\)2x = 4

\(\Rightarrow\)  x = 4 : 2

\(\Rightarrow\)  x = 2

c, 5^2x-3 - 2 . 5² = 5² . 3

5^2x-3 - 2 . 25 = 25 . 3

5^2x-3 - 50 = 75

5^2x-3 = 75 + 50

5^2x-3 = 125

5^2x-3 = 5³

2x - 3 = 3

2x = 3 + 3

2x = 6

  x = 6 : 2

  x = 3

a, 5^x = 125 suy ra 5^x = 5³ suy ra x = 3

b, 3^2x = 81 suy ra 3^2x = 3⁴ suy ra x = 2

c, 5^{2x - 3} - 2.5² = 5² . 3

suy ra 5^2x : 5³ = 5² .3 + 2. 5²

suy ra 5^2x : 5³ = 5² . 5

suy ra 5^2x = 5³ . 5² . 5³

5^2x = 5⁶ suy ra 2x = 6 suy ra x = 3

125 : 5^2 . (x-3) = 3

125 : 25 .(x-3) = 3

5 (x-3) =3

x-3 = 3 : 5

Đề bài sai hay sao ý?

2x -5 = 3

2x = 3+5 =8

x =4

 (19 .x+2.5^2 ): 14 = (13-8)^2 - 4^2

19x + 50) : 14 = 25 - 16

(19x+50) : 14 = 9

19x+50 = 3*14 = 126

 19x = 126-50 = 76

x = 76 / 19 = 4

\(a\)) \(125:5^2.\left(x-3\right)=3\)

\(5^3:5^2.\left(x-3\right)=3\)

\(5.\left(x-3\right)=3\)

\(5x-15=3\)

\(5x=3+15\)

\(5x=18\)

\(x=\frac{18}{5}\)\(.\)Vậy \(x=\frac{18}{5}\)

\(b\)) \(\left(2x-5\right)^3=27\)

\(\left(2x-5\right)^3=3^3\)

\(\Rightarrow2x-5=3\)

\(\Rightarrow2x=8\)

\(\Rightarrow x=4\)\(.\)Vậy \(x=4\)

\(c\))\(\left(19.x+2.5^2\right):14=\left(13-8\right)^2-4^2\)

\(\left(19.x+2.25\right):14=5^2-16\)

\(\left(19.x+2.25\right):14=25-16\)

\(\left(19.x+50\right):14=9\)

\(19.x+50=126\)

\(19.x=126-50\)

\(19.x=76\)

\(x=76:19\)

\(x=4\)\(.\)Vậy \(x=4\)

a,5^x=125

=>5^x=5^3

=>x=3

b,3^2x=81

=>3^2x=3^4

=>2x=4

=>x=4:2=2

c,5^2x-3-2*5^2=5^2+3

5^2x-3-50=75

5^2x-3=75+50=125

5^2x-3=5^3

=>2x-3=3

=>2x=3+3=6

=>6:2=3

k cho mk nhé

\(a,125=5\cdot5\cdot5=5^3\Leftrightarrow x=3\)

\(b,81=3\cdot3\cdot3\cdot3=3^4\Leftrightarrow2x=4\Leftrightarrow x=4:2\Leftrightarrow x=2\)

\(c,5^{2x-3}-2\cdot5^2=5^2\cdot3\)

\(\Leftrightarrow5^{2x-3}=2\cdot5^2+5^2\cdot3\)

\(\Leftrightarrow5^{2x-3}=5^2\cdot\left(2+3\right)\)

\(\Leftrightarrow5^{2x-3}=5^2\cdot5\Leftrightarrow5^{2x-3}=5^3\)

\(\Leftrightarrow2x-3=3\Leftrightarrow2x=3+3\Leftrightarrow2x=6\Leftrightarrow x=6:2\Leftrightarrow x=3\)

a: =>2x=-18+5=-13

=>x=-13/2

b: =>3^x-1=81

=>x-1=4

=>x=5

c: =>4(5-x)=24

=>5-x=6

=>x=-1

a) x = 3 .                              

a) 5^x = 125

5^x = 5³

=> x = 3

b)  ( mình bó tay )

c) 5^2x-3 -  2.5² = 5² .3

5^2x-3 - 50 = 75

5^2x-3  = 75 + 50

5^2x-3  = 125

5^2x-3  = 5³

2x-3 = 3

2x = 3+3

2x = 6

x = 6 : 2

x = 3

ai trả lời nhanh mk k cho

a, x = 3

b, x ko có giá trị để 32^x = 81

c,  5^2x-3- 50 =75

    5^2x-3       = 75 + 50

    5^2x-3        = 125   \(\Rightarrow\)x = 8