`|1-x|=3`
`@TH1:1-x=3=>x=1-3=-2`
`@TH2:1-x=-3=>x=1-(-3)=1+3=4`
Vậy `x=-2` hoặc `x=4`
\(\left|1-x\right|=3\\ \Leftrightarrow\left[{}\begin{matrix}1-x=3\\1-x=-3\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\\x=4\end{matrix}\right.\)
=> 1 + x = 3 hoặc 1+ x = -3
TH1: 1 + x = 3
=> x = 2
TH2: 1 + x = -3
=> x = -4
Vậy x = 2 hoặc x = -4