a: |-x+5|=x+1
=>|x-5|=x+1
\(\Leftrightarrow\left\{{}\begin{matrix}x>=-1\\\left(x-5\right)^2-\left(x+1\right)^2=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=-1\\x^2-10x+25-x^2-2x-1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>=-1\\-12x+24=0\end{matrix}\right.\)
=>x=2
b: |1-3x|=2x
=>|3x-1|=2x
\(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(3x-1-2x\right)\left(3x-1+2x\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(x-1\right)\left(5x-1\right)=0\end{matrix}\right.\Leftrightarrow x\in\left\{1;\dfrac{1}{5}\right\}\)
c: |2x+1|=|x-2|
=>2x+1=x-2 hoặc 2x+1=-x+2
=>x=-3 hoặc 3x=1
=>x=-3 hoặc x=1/3
