Goi \(B\left(x_0;y_0\right)\) la tiep diem \(\Rightarrow x_0=1\Rightarrow y_0=3m\)
\(y'=3x^2-4x+3m\Rightarrow y'\left(1\right)=3-4+3m=3m-1\)
\(\Rightarrow pttt:y=\left(3m-1\right)\left(x-1\right)+3m\)
\(A\left(1;3\right)\in pttt\Rightarrow\left(3m-1\right)\left(1-1\right)+3m=3\Leftrightarrow3m=3\Leftrightarrow m=1\)