\(\Rightarrow\left(\dfrac{33}{11}\right)^{2x}=81\Rightarrow3^{2x}=3^4\Rightarrow x=2\)

a) 2³.(20 - 2x) = 4.2⁵

8.(20 - 2x) = 4.32

8.(20 - 2x) = 128

20 - 2x = 128 : 8

20 - 2x = 16

2x = 20 - 16

2x = 4

x = 4 : 2

x = 2

b) 3²⁺ˣ = 81

3²⁺ˣ = 3⁴

2 + x = 4

x = 4 - 2

x = 2

a. (2x-1)⁴=81

=>(2x-1)⁴=3⁴

=>2x-1=3

=>2x=3+1

=>2x=4

=>x=4:2

=>x=2

b.(x-1)⁵=-32

=>(x-1)⁵=(-2)⁵

=>x-1=-2

=>x=-2+1

=>x=-1

c.(2x-1)⁶=(2x-1)⁸

mà chỉ có: (-1)⁶=(-1)⁸; 0⁶=0⁸; 1⁶=1⁸

=> để (2x-1) \(\in\){-1;0;1} thì x \(\in\){0; 1/2; 1}

(2x-1)^4=3^4

=>2x-1=3

=>2x=4

=>x=2

ai h minh minh h lai cho

minh ko bit

Bài 2: 

a: Ta có: \(2^{x+1}\cdot3^y=12^x\)

\(\Leftrightarrow2^{x+1}\cdot3^y=2^{2x}\cdot3^x\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+1=2x\\x=y\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=1\end{matrix}\right.\)

a ) \(\left(2x-1\right)^4=81\)

\(\Leftrightarrow\left(2x-1\right)^4=3^4\)

\(\Leftrightarrow2x-1=3\)

\(\Leftrightarrow x=2\)

Vậy \(x=2.\)

b ) \(\left(x-1\right)^5=-32\)

\(\Leftrightarrow\) \(\left(x-1\right)^5=-2^5\)

\(\Leftrightarrow x-1=-2\)

\(\Leftrightarrow x=-1\)

Vậy \(x=-1.\)

c ) \(\left(2x-1\right)^6=\left(2x-1\right)^8\)

\(\Leftrightarrow\left(2x-1\right)^6-\left(2x-1\right)^8=0\)

\(\Leftrightarrow\left(2x-1\right)^6\left[1-\left(2x-1\right)^2\right]=0\)

\(\Leftrightarrow\left(2x-1\right)^6\left[\left(1-2x+1\right)\left(1+2x-1\right)\right]=0\)

\(\Leftrightarrow\left(2x-1\right)^6\left[\left(2-2x\right).2x\right]=0\)

\(\Leftrightarrow\left[{}\begin{matrix}\left(2x-1\right)^6=0\\2-2x=0\\2x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\2x=2\\x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=1\\x=0\end{matrix}\right.\)

Vậy ...............

a) (2x-1)⁴​=81

\(\Leftrightarrow\)\(\left[\begin{array}{} (2x-1)^4=(3)^4\\ (2x-1)^4=(-3)^4 \end{array}\right.\)

\(\Rightarrow\)\(\left[\begin{array}{} 2x-1=3\\ 2x-1=-3 \end{array}\right.\)

\(\Rightarrow\)\(\left[\begin{array}{} 2x=3+1\\ 2x=-3+1 \end{array}\right.\)

\(\Rightarrow\)\(\left[\begin{array}{} 2x=4\\ 2x=-2 \end{array}\right.\)

\(\Rightarrow\)\(\left[\begin{array}{} x=4:2\\ x=-2:2 \end{array}\right.\)

\(\Rightarrow\)\(\left[\begin{array}{} x=2\\ x=-1 \end{array}\right.\)

Vậy x=2 hoặc x=-1

b) (x-1)⁵​= -32

\(\Leftrightarrow\)\( (x-1)^5=(-2)^5 \)

\(\Rightarrow\)\( (x-1)=-2 \)

\(\Rightarrow\)\( x=-2+1 \)

\(\Rightarrow\)\( x=-1 \)

Vậy x=-1

c) ( 2x-1)6​= ( 2x-1)8

\(\Leftrightarrow\) (2x-1)⁶=(2x-1)⁸.

\(\Leftrightarrow\)(2x-1)⁸-(2x-1)⁶=0.

\(\Leftrightarrow\)(2x-1)⁶)[(2x-1)²-1]=0.

\(\Leftrightarrow\)(2x-1)⁶(2x-1+1)(2x+1+1)=0.

\(\Leftrightarrow\)(2x-1)⁶2x(2x+2)=0.

\(\Leftrightarrow\)(2x-1)⁶<=>2x(2x-1)=0.\(\Rightarrow x=\dfrac{1}{2}\)

hoặc 2x=0\(\Rightarrow\)x=0

hoặc 2x+2=0\(\Rightarrow\)2x=-2\(\Leftrightarrow\)x=-2:2\(\Leftrightarrow\)x=-1

Vậy x=\(\dfrac{1}{2}\)hoặc x=0 hoặc x=-1

Chúc bạn học tốt !!!

a: 3x=81

nên x=27

b: \(5\cdot4^x=80\)

\(\Leftrightarrow4^x=16\)

hay x=2

c: \(2^x=4^5:4^3\)

\(\Leftrightarrow2^x=2^4\)

hay x=4