Ta có: \(y'=\dfrac{\left(2x-m\right)\left(x-1\right)-\left(x^2-mx+m\right)}{\left(x-1\right)^2}\)
\(\Leftrightarrow y'=\dfrac{x^2-2x}{\left(x-1\right)^2}\)
\(\Leftrightarrow y'=0\Rightarrow x^2-2x=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\end{matrix}\right.\)
Suy ra:
Khi \(x=0\Rightarrow y=-m\Rightarrow A\left(0;-m\right)\)
Khi \(x=2\Rightarrow y=4-m\Rightarrow B\left(2;4-m\right)\)
\(\Rightarrow\overrightarrow{AB}=\left(2;4\right)\Rightarrow AB=\sqrt{2^2+4^2}=2\sqrt{5}\)