\(\frac{25}{5^x}\)=\(\frac{1}{125}\)

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13 tháng 9 2017

\(\frac{25}{5^x}=\frac{1}{125}\Rightarrow25.125=5^x.1\)

\(3125=5^x\)

\(5^5=5^x\)

\(\Rightarrow x=5\)

13 tháng 9 2017

25/5^x=25/5^5

2^8+2^2+3=288

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

2x-1=3

2x=4

x=2

14 tháng 7 2016

\(\left(2x-5\right)^2=0,81\)

\(\left(2x-5\right)^2=0,9^2\)

\(\Rightarrow2x-5=0,9\)

\(2x=0,9+5\)

\(2x=5,9\)

\(x=5,9:2\)

\(x=2,95\)

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\(\left(x-\frac{1}{3}\right)^3=0,027\)

\(\left(x-\frac{1}{3}\right)^3=0,3^3\)

\(\Rightarrow x-\frac{1}{3}=0,3\)

\(x=0,3+\frac{1}{3}\)

\(x=\frac{19}{30}\)

\(\left(2x-5\right)^2=0,81\)

\(\Rightarrow2x-5=0,9\)

\(\Rightarrow2x=5,9\)

\(\Rightarrow x=2,95\)

\(\left(x-\frac{1}{3}\right)^3=0,027\)

\(\Rightarrow x-\frac{1}{3}=0,3\)

\(\Rightarrow x=\frac{19}{30}\)

28 tháng 9 2018

a/ \(\left(\frac{1}{5}\right)^x=\left(\frac{1}{5^3}\right)^3=\left(\frac{1}{5}\right)^9\Rightarrow x=9\)

b/ \(\left(\frac{3}{5}\right)^x=\left(\frac{3^2}{5^2}\right)^3=\left(\frac{3}{5}\right)^6\Rightarrow x=6\)

c\(2^{3-2x}=\left(2^3\right)^3=2^9\Rightarrow3-2x=9\Rightarrow x=-3\)

d/ \(2^{3x+1}=32^2=\left(2^5\right)^2=2^{10}\Rightarrow3x+1=10\Rightarrow x=3\)

e/ \(3^{6-3x}=81^3=\left(3^4\right)^3=3^{12}\Rightarrow6-3x=12\Rightarrow x=-2\)

28 tháng 9 2018

\(\left(\frac{1}{5}\right)^x=\left(\frac{1}{125}\right)^3\Leftrightarrow\left(\frac{1}{5}\right)^x=\left[\left(\frac{1}{5}\right)^3\right]^3\Leftrightarrow\left(\frac{1}{5}\right)^x=\left(\frac{1}{5}\right)^9\Leftrightarrow x=9\)

\(\left(\frac{3}{5}\right)^x=\left(\frac{9}{25}\right)^3\Leftrightarrow\left(\frac{3}{5}\right)^x=\left[\left(\frac{3}{5}\right)^2\right]^3\Leftrightarrow\left(\frac{3}{5}\right)^x=\left(\frac{3}{5}\right)^6\Leftrightarrow x=6\)

\(2^{3-2x}=8^3\Leftrightarrow2^{3-2x}=\left(2^3\right)^3\Leftrightarrow2^{3-2x}=2^9\Leftrightarrow3-2x=9\)

\(\Leftrightarrow2x=3-9\Leftrightarrow2x=-6\Leftrightarrow x=\left(-6\right):2\Leftrightarrow x=-3\)

Các phép còn lại làm tương tự bn nha !

29 tháng 11 2016

a)\(\left(-3\right)^{x+3}=-\frac{1}{27}\)

\(\left(-3\right)^{x+3}=\left(-\frac{1}{3}\right)^3\)

\(\left(-3\right)^{x+3}=\left(-\frac{3^0}{3^1}\right)^3\)

\(\left(-3\right)^{x+3}=\left(-3^{-1}\right)^3\)

\(\left(-3\right)^{x+3}=\left(-3\right)^{-3}\)

\(\Rightarrow x+3=-3\)

\(\Rightarrow x=-6\)

b)\(\left(-6\right)^{2x+2}=\frac{1}{36}\)

\(\left(-6\right)^{2x+2}=\left(-\frac{1}{6}\right)^2\)

\(\left(-6\right)^{2x+2}=\left(-\frac{6^0}{6^1}\right)^2\)

\(\left(-6\right)^{2x+2}=\left(-6^{-1}\right)^2\)

\(\left(-6\right)^{2x+2}=\left(-6\right)^{-2}\)

\(\Rightarrow2x+2=-2\)

\(\Rightarrow2x=-4\)

\(\Rightarrow x=-2\)

c)\(\left(-3\right)^{x+5}=\frac{1}{81}\)

\(\left(-3\right)^{x+5}=\left(-\frac{1}{3}\right)^4\)

\(\left(-3\right)^{x+5}=\left(-\frac{3^0}{3^1}\right)^4\)

\(\left(-3\right)^{x+5}=\left(-3^{-1}\right)^4\)

\(\left(-3\right)^{x+5}=\left(-3\right)^{-4}\)

\(\Rightarrow x+5=-4\)

\(\Rightarrow x=-9\)

29 tháng 11 2016

d)\(\left(\frac{1}{9}\right)^x=\left(\frac{1}{27}\right)^6\)

\(\left[\left(\frac{1}{3}\right)^2\right]^x=\left[\left(\frac{1}{3}\right)^3\right]^6\)

\(\left(\frac{1}{3}\right)^{2x}=\left(\frac{1}{3}\right)^{18}\)

\(\Rightarrow2x=18\)

\(\Rightarrow x=9\)

e)\(\left(\frac{4}{9}\right)^x=\left(\frac{8}{27}\right)^6\)

\(\left[\left(\frac{2}{3}\right)^2\right]^x=\left[\left(\frac{2}{3}\right)^3\right]^6\)

\(\left(\frac{2}{3}\right)^{2x}=\left(\frac{2}{3}\right)^{18}\)

\(\Rightarrow2x=18\)

\(\Rightarrow x=9\)

4 tháng 12 2017

a) \(1\frac{2}{5}x+\frac{4}{5}=\frac{-7}{10}\)

\(\frac{7}{5}x=\frac{-7}{10}-\frac{4}{5}\)

\(\frac{7}{5}x=\frac{-3}{2}\)

\(x=\frac{-15}{14}\)

vậy \(x=\frac{-15}{14}\)

b) \(\left(x+\frac{1}{2}\right)^2=\frac{4}{25}\)

\(\left(x+\frac{1}{2}\right)^2=\left(\frac{2}{5}\right)^2\)

\(\Rightarrow x+\frac{1}{2}=\frac{2}{5}\)

\(\Rightarrow x=\frac{2}{5}-\frac{1}{2}\)

\(\Rightarrow x=\frac{-1}{10}\)

vậy \(x=\frac{-1}{10}\)

4 tháng 12 2017

a) \(x=\frac{-15}{14}\)

b) \(x=\frac{-1}{10}\)

a: =>x-8/5=1/20-1/10=-1/20

=>x=-0,05+1,6=1,55

b: =>x-3/2=4/3 hoặc x-3/2=-4/3

=>x=17/6 hoặc x=1/6

c: =>\(\left|x-\dfrac{1}{3}\right|=\dfrac{5}{2}-\dfrac{1}{4}+\dfrac{2}{3}=\dfrac{35}{12}\)

=>x-1/3=35/12 hoặc x-1/3=-35/12

=>x=39/12=13/4 hoặc x=-31/12

d: =>|x-5/8|=3/4

=>x-5/8=3/4 hoặc x-5/8=-3/4

=>x=11/8 hoặc x=-1/8