Question

3. Tìm x

a. \(\left|x\right|=9,5\)

b. \(\left|x+2\right|=\left|\dfrac{-3}{20}\right|\)

c. \(\left|x\right|=-2,4\)

d. \(\left|x+2,8\right|=1,5\)

Answer 1

a) \(\left|x\right|=9,5\Leftrightarrow\left[{}\begin{matrix}x=9,5\\x=-9,5\end{matrix}\right.\)

b) \(\left|x+2\right|=\left|\dfrac{-3}{20}\right|=\dfrac{3}{20}\Leftrightarrow\left[{}\begin{matrix}x+2=\dfrac{3}{20}\\x+2=-\dfrac{3}{20}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{29}{15}\\x=-\dfrac{31}{15}\end{matrix}\right.\)

c) \(\left|x\right|=-2,4\Rightarrow x\in\varnothing\left(\left|x\right|\ge0\right)\)

d) \(\left|x+2,8\right|=1,5\Leftrightarrow\left[{}\begin{matrix}x+2,8=1,5\\x+2,8=-1,5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1,3\\x=-4,3\end{matrix}\right.\)