Question

2. Tìm x, biết

a) 2\(\left|x\right|\)=1,8

b) \(\left|2x-\dfrac{1}{2}\right|\)-0,4=\(\dfrac{3}{5}\)

Giúp mình với

Answer 1

a, \(2\left|x\right|=1,8\Rightarrow\left|x\right|=0,9\)

\(\Rightarrow\left\{{}\begin{matrix}x=-0,9\\x=0,9\end{matrix}\right.\)

Vậy...........

b, \(\left|2x-\dfrac{1}{2}\right|-0,4=\dfrac{3}{5}\)

\(\Rightarrow\left|2x-\dfrac{1}{2}\right|=1\)

\(\Rightarrow\left\{{}\begin{matrix}2x-\dfrac{1}{2}=1\\2x-\dfrac{1}{2}=-1\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\dfrac{3}{4}\\x=-\dfrac{1}{4}\end{matrix}\right.\)

Vậy.........

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Answer 2

\(2\left|x\right|=1,8\)

\(\Rightarrow\left|x\right|=0,9\)

\(\Rightarrow\left\{{}\begin{matrix}x=0,9\\x=-0,9\end{matrix}\right.\)

\(\left|2x-\dfrac{1}{2}\right|-0,4=\dfrac{3}{5}\)

\(\Rightarrow\left|2x-\dfrac{1}{2}\right|=1\)

\(\Rightarrow\left\{{}\begin{matrix}2x-\dfrac{1}{2}=1\Rightarrow2x=\dfrac{3}{2}\Rightarrow x=\dfrac{3}{4}\\2x-\dfrac{1}{2}=-1\Rightarrow2x=-\dfrac{1}{2}\Rightarrow x=-\dfrac{1}{4}\end{matrix}\right.\)

Answer 3

2. Tìm x biết:
a) Ta có: \(2\left|x\right|=1,8\)

\(\Rightarrow \left|x\right|=\dfrac{1,8}{2}\)

\(\Rightarrow\left|x\right|=0,9\)

\(\Rightarrow x=\pm0,9\)

Vậy \(x=\pm0,9\)

b) Ta có: \(\left|2x-\dfrac{1}{2}\right|-0,4=\dfrac{3}{5}\)

\(\Rightarrow\left|2x-\dfrac{1}{2}\right|=\dfrac{3}{5}+0,4\)

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

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{4}\\x=-\dfrac{1}{4}\end{matrix}\right.\)

Vậy \(x=\dfrac{3}{4}\) hoặc \(x=-\dfrac{1}{4}\)

Answer 4

a, \(2\left|x\right|=1,8\)

\(\left|x\right|=1,8:2\)

\(\left|x\right|=0,9\)

\(\Rightarrow x=0,9\) hoặc \(x=-0,9\)

b, \(\left|2x-\dfrac{1}{2}\right|-0.4=\dfrac{3}{5}\)

\(\left|2x-0,5\right|-0,4=0.6\)

\(\left|2x-0,5\right|=0,6+0,4\)

\(\left|2x-0,5\right|=1\)

\(\Rightarrow\left[{}\begin{matrix}2x-0,5=1\\2x-0,5=-1\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}2x=1,5\\2x=-0,5\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=0,75\\x=-0,25\end{matrix}\right.\)

Vậy \(x=0,75\) hoặc \(x=-0,25\)