a, (3x+1)³=-27                    b, (1/2.2^x+4.2^x ) = 9.25

=> ( 3x+1)³=(-3)³                    => [ 2^x.(1/2+4 ) ]=9.25                                c, ( 3x-2)⁵= - 243

=> 3x+1=-3                       => 2^x.9/2 = 225                                           => ( 3x-2)⁵=(-3)⁵

=>3x=-4                            => 2^x        = 225:9/2                                     => 3x-2=-3

=>  x = -4/3                       => 2^x       = 50 (ko có trường hợp nào )         => 3x= -1

                                                                                                            => x=-1/3

\(27^3.9^4.243=\left(3^3\right)^3.\left(3^2\right)^4.3^5\)

                        \(=3^9.3^8.3^5\)

                         \(=3^{22}\)

Học tốt nha!!!

\(27^3.9^4.243=3^{3.3}.3^{2.4}.3^5\)

\(3^9.3^8.3^5=3^{22}\)

\(25^3.125^2=5^{2.3}.5^{3.2}=5^6.5^6=5^{12}\)

a: =>4^x=640

=>\(x\in\varnothing\)

b: =>\(3^{-2x}\cdot3^{3x}=243\)

=>3^x=243

=>x=5

`a)x^3=343=7^3`

`=>x=7`

Vậy `x=7`

`b)(x-2,5)^4=(x-2,5)^2`

`=>(x-2,5)^2[(x-2,5)^2-1]=0`

`+)(x-2,5)^2=0<=>x=2,5`

`+)(x-2,5)^2=1`

`TH1:x-2,5=1<=>x=3,5`

`th2:x-2,5=-1<=>x=1,5`

Vậy `x=0` hoặc `x=1,5` hoặc `x=3,5

`c)x^8/243=27`

`=>x^8=27.243`

`=>x^8=3^3*3^5=3^8`

`=>x=+-3`

Giải:

a) \(x^3=343\) 

\(\Rightarrow x^3=7^3\) 

\(\Rightarrow x=7\) 

b) \(\left(x-2,5\right)^4=\left(x-2,5\right)^2\) 

Vì có cùng cơ số nhưng lại khác mũ thì \(\left(x-2,5\right)\in\left\{0;1\right\}\) 

TH1:

\(\Rightarrow x-2,5=0\) 

\(\Rightarrow x=2,5\) 

TH2:

\(\Rightarrow\left[{}\begin{matrix}x-2,5=1\\x-2,5=-1\end{matrix}\right.\) 

\(\Rightarrow\left[{}\begin{matrix}x=3,5\\x=1,5\end{matrix}\right.\) 

c) \(\dfrac{x^8}{243}=27\) 

\(\Rightarrow x^8=3^3.3^5\) 

\(\Rightarrow x^8=3^8\) 

\(\Rightarrow x=\pm3\)

\(243^5=\left(3^5\right)^5=3^{25}\)

\(3.27^8=3.\left(3^3\right)^8=3.3^{24}=3^{25}\)

Vậy\(243^5=3.27^8\)

\(243^5=\left(3^5\right)^5=3^{25}\)

\(3.27^8=3.\left(3^3\right)^8=3.3^{24}=3^{25}\)

Vậy suy ra : \(243^5=3.27^8\)

Như đặc cầu

a) 3^x=27

3^x=3³

x=3

b.2^x:2^3=1

2^x:8=1

2^x=1x8

2^x=8

2^x=2³

x=3

c.27<3^x<243

3³=27(loại)

3⁴=81 (lấy)

3⁵=243(loại)

vậy x=4

d.4^x-^3=36

=(3^3)^3x(3^2)4x3^5

=3^9x3^8x3^5

=3^22

roi viet ro cach giai giup minh nha

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

⇔\(x^2-2.x.1,2+1,2^2=4\)

⇔\(x^2-2,4x+1,44=4\)

⇔\(x^2-2,4x=4-1,44\)

⇔\(x\left(x-2,4\right)=2,56\)

⇔\(x=2,56\) hoặc \(x-2,4=2,56\)

⇔\(x=2,56\) hoặc \(x=4,96\)

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

\(\Leftrightarrow x-1,2=4\)

\(\Leftrightarrow x=5,2\)

b) \(\left(x+1\right)^3=-125=\left(-5\right)^3\)

\(\Leftrightarrow x+1=-5\)

\(\Leftrightarrow x=-6\)

c) \(\left(x+1,5\right)^8+\left(2,7-y\right)^{10}=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+1,5=0\\2,7-y=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=-1,5\\y=2,7\end{matrix}\right.\)