Question

\(\left|x-\dfrac{4}{5}\right|\)-\(\dfrac{3}{4}\)=0

Answer 1

Giải:

\(\left|x-\dfrac{4}{5}\right|-\dfrac{3}{4}=0\)

\(\left|x-\dfrac{4}{5}\right|=0+\dfrac{3}{4}=\dfrac{3}{4}\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-\dfrac{4}{5}=\dfrac{3}{4}\\x-\dfrac{4}{5}=-\dfrac{3}{4}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3}{4}+\dfrac{4}{5}\\x=-\dfrac{3}{4}+\dfrac{4}{5}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{31}{20}\\x=\dfrac{1}{20}\end{matrix}\right.\)

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Answer 2

\(\left|x-\dfrac{4}{5}\right|-\dfrac{3}{4}=0\)

xét th1: \(x\ge\dfrac{4}{5}\) thì \(\left|x-\dfrac{4}{5}\right|-\dfrac{3}{4}=0\Leftrightarrow x-\dfrac{4}{5}-\dfrac{3}{4}=0\Leftrightarrow x=\dfrac{4}{5}+\dfrac{3}{4}=\dfrac{31}{20}\) th2: \(x< \dfrac{4}{5}\) thì \(\left|x-\dfrac{4}{5}\right|-\dfrac{3}{4}=0\Leftrightarrow\dfrac{4}{5}-x-\dfrac{3}{4}=0\Leftrightarrow x=\dfrac{4}{5}-\dfrac{3}{4}=\dfrac{1}{20}\)

vậy \(x=\dfrac{31}{20};x=\dfrac{1}{20}\)