Đáp án+Giải thích các bước giải:
`a)|1-3x|+5=9`
`\to |1-3x|=9-5`
`\to |1-3x|=4`
\(\to\left[ \begin{array}{l}1-3x=4\\1-3x=-4\end{array} \right.\)
\(\to\left[ \begin{array}{l}3x=1-4\\3x=1+4\end{array} \right.\)
\(\to\left[ \begin{array}{l}3x=-3\\3x=5\end{array} \right.\)
\(\to\left[ \begin{array}{l}x=-1\\x=\dfrac{5}{3}\end{array} \right.\)
Vậy `x\in\{-1;5/3\}`
`b)|2x|-1/2=1`
`\to |2x|=1+1/2`
`\to |2x|=3/2`
\(\to\left[ \begin{array}{l}2x=\dfrac{3}{2}\\2x=-\dfrac{3}{2}\end{array} \right.\)
\(\to\left[ \begin{array}{l}x=\dfrac{3}{2}:2\\x=-\dfrac{3}{2}:2\end{array} \right.\)
\(\to\left[ \begin{array}{l}x=\dfrac{3}{4}\\x=-\dfrac{3}{4}\end{array} \right.\)
Vậy `x\in\{3/4;-3/4\}`
