Question

Giải phương trình:|x - 1|=7x+2

Answer 1

\(\left|x-1\right|=7x+2\\ \Leftrightarrow\left[{}\begin{matrix}x-1=7x+2\left(x\ge1\right)\\x-1=-7x-2\left(x< 1\right)\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x-7x=2+1\\x+7x=-2+1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}-6x=3\\8x=-1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\left(ktm\right)\\x=-\dfrac{1}{8}\left(tm\right)\end{matrix}\right.\\ Vậy.S=\left\{-\dfrac{1}{8}\right\}\)