a/ Với \(x\ge2\) pt trở thành:
\(x-2+3x-9=0\)
\(\Leftrightarrow4x-11=0\Rightarrow x=\frac{11}{4}\) (nhận)
Với \(x< 2\) pt trở thành:
\(2-x+3x-9=0\)
\(\Leftrightarrow2x-7=0\Rightarrow x=\frac{7}{2}>2\left(l\right)\)
b/
\(\left(x^2-5x+1\right)^2-2\left(x^2-5x+1\right)+1=0\)
\(\Leftrightarrow\left(x^2-5x+1-1\right)^2=0\)
\(\Leftrightarrow\left(x^2-5x\right)^2=0\)
\(\Leftrightarrow x^2-5x=0\)
\(\Leftrightarrow x\left(x-5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=5\end{matrix}\right.\)