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26 tháng 10 2016

a) \(3-\sqrt{x}=\)0

\(\sqrt{x}=0+3\)

\(\sqrt{x}=3\)

mà :\(\sqrt{9}=3\)

=> x = 9

26 tháng 10 2016

Thank you very much!

25 tháng 11 2019

1.

a) \(x-4\sqrt{x}=0\)

\(\Rightarrow\sqrt{x}.\left(\sqrt{x}-4\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}\sqrt{x}=0\\\sqrt{x}-4=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\\sqrt{x}=0+4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\\sqrt{x}=4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=16\end{matrix}\right.\)

Vậy \(x\in\left\{0;16\right\}.\)

b) \(\left|\frac{3}{5}\sqrt{x}-\frac{1}{20}\right|-\frac{3}{4}=\frac{1}{5}\)

\(\Rightarrow\left|\frac{3}{5}\sqrt{x}-\frac{1}{20}\right|=\frac{1}{5}+\frac{3}{4}\)

\(\Rightarrow\left|\frac{3}{5}\sqrt{x}-\frac{1}{20}\right|=\frac{19}{20}.\)

\(\Rightarrow\left[{}\begin{matrix}\frac{3}{5}\sqrt{x}-\frac{1}{20}=\frac{19}{20}\\\frac{3}{5}\sqrt{x}-\frac{1}{20}=-\frac{19}{20}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}\frac{3}{5}\sqrt{x}=1\\\frac{3}{5}\sqrt{x}=-\frac{9}{10}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}\sqrt{x}=1:\frac{3}{5}\\\sqrt{x}=\left(-\frac{9}{10}\right):\frac{3}{5}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}\sqrt{x}=\frac{5}{3}\\\sqrt{x}=-\frac{3}{2}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{25}{9}\\x\in\varnothing\end{matrix}\right.\)

Vậy \(x=\frac{25}{9}.\)

Câu c) làm tương tự như câu b).

Chúc bạn học tốt!

13 tháng 11 2017

\(a,2\sqrt{x}+3=0\)

\(\Leftrightarrow2\sqrt{x}=-3\)

\(\Leftrightarrow\sqrt{x}=-\frac{3}{2}\)( loại )

\(b,\frac{5}{12}\sqrt{x}-\frac{1}{6}=\frac{1}{3}\Leftrightarrow\frac{5}{12}\sqrt{x}=\frac{1}{2}\Leftrightarrow\sqrt{x}=\frac{6}{5}\Leftrightarrow x=\frac{36}{25}\)

\(c,\sqrt{x+3}+3=0\Leftrightarrow\sqrt{x+3}=-3\)( loại )

20 tháng 12 2018

a) \(\frac{1}{4}+\frac{1}{3}:2x=-5\)

\(\frac{1}{3}:2x=\frac{-21}{4}\)

\(2x=\frac{-4}{63}\)

\(x=\frac{2}{63}\)

20 tháng 12 2018

b) \(\left(3x-\frac{1}{4}\right)\left(x+\frac{1}{2}\right)=0\)

\(\Rightarrow\orbr{\begin{cases}3x-\frac{1}{4}=0\\x+\frac{1}{2}=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{1}{12}\\x=\frac{-1}{2}\end{cases}}\)

Vậy.........

19 tháng 2 2018

      \(\frac{x+2}{327}+\frac{x+3}{326}+\frac{x+4}{325}+\frac{x+5}{324}+\frac{x+349}{5}=0\)

\(\Leftrightarrow\)\(\frac{x+2}{327}+1+\frac{x+3}{326}+1+\frac{x+4}{325}+1+\frac{x+5}{324}+1 +\frac{x+349}{5}-4=0\)

\(\Leftrightarrow\)\(\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)

\(\Leftrightarrow\)\(\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)=0\)

\(\Leftrightarrow\)\(x+329=0\)   (vì  1/327 + 1/326 + 1/325 + 1/324 + 1/5  khác  0  )

\(\Leftrightarrow\)\(x=-329\)

19 tháng 2 2018

Bài 1 : 

\(\frac{x+2}{327}+\frac{x+3}{326}+\frac{x+4}{325}+\frac{x+5}{324}+\frac{x+349}{5}=0\)

\(\Leftrightarrow\)\(\left(\frac{x+2}{327}+1\right)+\left(\frac{x+3}{326}+1\right)+\left(\frac{x+4}{325}+1\right)+\left(\frac{x+5}{324}+1\right)+\left(\frac{x+349}{5}-4\right)=0\)

\(\Leftrightarrow\)\(\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)

\(\Leftrightarrow\)\(\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)=0\)

Vì \(\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)\ne0\)

\(\Rightarrow\)\(x+329=0\)

\(\Rightarrow\)\(x=-329\)

Vậy \(x=-329\)

5 tháng 11 2015

a) \(\sqrt{2x+\frac{5}{4}}=\frac{3}{2}\)

\(2x+\frac{5}{4}=\frac{9}{4}\)

2x = 1

\(x=\frac{1}{2}\)

b) \(\sqrt{\frac{x}{3}-\frac{7}{6}}=\frac{1}{6}\)

\(\frac{x}{3}-\frac{7}{6}=\frac{1}{36}\)

\(\frac{x}{3}=\frac{43}{36}\)

\(x=\frac{43\cdot3}{36}=\frac{129}{36}\)