\(9.27\le\left(\frac{1}{3}\right)^x\le27.243\)

\(\Rightarrow243\le\left(\frac{1}{3}\right)^x\le6561\)

\(\Rightarrow\left(\frac{1}{3}\right)^{-5}\le\left(\frac{1}{3}\right)^x\le\left(\frac{1}{3}\right)^{-8}\)

\(\Rightarrow-5\le x\le-8\)

\(\Rightarrow\left\{{}\begin{matrix}x=-5\\x=-6\\x=-7\\x=-8\end{matrix}\right.\)

Vậy \(x\in\left\{-5;-6;-7;-8\right\}.\)

Chúc bạn học tốt!

1. Tìm x, biết :

a. ( x - \(\frac{3}{4}\)) \(^2\)= 0

=> x - \(\frac{3}{4}\)= 0

=> x = 0 + \(\frac{3}{4}\)

=> x = \(\frac{3}{4}\)

b. ( x + \(\frac{1}{2}\)) \(^2\)= \(\frac{9}{64}\)

=> ( x + \(\frac{1}{2}\)) \(^2\)= ( \(\frac{3}{8}\)) \(^2\)

=> x + \(\frac{1}{2}\)= \(\frac{3}{8}\)

=> x = \(\frac{3}{8}\)- \(\frac{1}{2}\)

=> x = \(\frac{-1}{8}\)

c.  \(\frac{\left(-2\right)^x}{16}=-8\)

=> \(\frac{\left(-2\right)^x}{16}=\frac{-8}{1}=\frac{-128}{16}\)

=> ( -2)\(^x\)= -128

=> ( -2 ) \(^x\)= ( -2) \(^7\)

=> x = 7

a: \(\Leftrightarrow\dfrac{1}{2}-\dfrac{7}{12}< x< \dfrac{1}{48}+\dfrac{5}{48}=\dfrac{6}{48}=\dfrac{1}{8}\)

\(\Leftrightarrow-\dfrac{1}{12}< x< \dfrac{1}{8}\)

=>x=0

c: \(\Leftrightarrow x=\dfrac{-1}{2}\cdot\dfrac{1}{4}=\dfrac{-1}{8}\)

d: \(\Leftrightarrow x^8=x^7\)

=>x(x-1)=0

=>x=0(loại) hoặc x=1(nhận)

e: \(\Leftrightarrow3^x=\dfrac{3^{10}}{3^9}=3\)

hay x=1

f: =>x-1=20

hay x=21

a: |x-1/2|=7/2

=>x-1/2=7/2 hoặc x-1/2=-7/2

=>x=4 hoặc x=-3

b: \(x:\dfrac{3}{8}+\dfrac{5}{8}=x\)

=>8/3x-x=-5/8

=>5/3x=-5/8

hay x=-5/8:5/3=-5/8x3/5=-15/40=-3/8

c: \(\dfrac{5}{6}-\left|x-\dfrac{1}{2}\right|=\dfrac{15}{18}=\dfrac{5}{6}\)

=>|x-1/2|=0

=>x-1/2=0

hay x=1/2

e: \(\left(5x-3\right)^2-\dfrac{1}{64}=0\)

=>(5x-3)²=1/64

=>5x-3=1/8 hoặc 5x-3=-1/8

=>5x=25/8 hoặc 5x=23/8

=>x=5/8 hoặc x=23/40