Đáp án:
Giải thích các bước giải:
$\begin{array}{l}
y' = {x^2} - 4x + 1\\
Tiep\,tuyen\,song\,song\,y = - 2x + 5\,nen\,k = - 2\\
\Rightarrow - 2 = {x^2} - 4x + 1 \Leftrightarrow {x^2} - 4x + 3 = 0 \Leftrightarrow \left[ \begin{array}{l}
x = 1\\
x = 3
\end{array} \right.\\
Voi\,x = 1 \Rightarrow y = \frac{4}{3} \Rightarrow tiep\,tuyen\,y = - 2\left( {x - 1} \right) + \frac{4}{3} = - 2x + \frac{{10}}{3}\\
Voi\,x = 3 \Rightarrow y = - 4 \Rightarrow tiep\,tuyen\,y = - 2\left( {x - 3} \right) - 4 = - 2x + 2
\end{array}$
