The synthetic division table is:
$$ \begin{array}{c|rrrr}2&3&-1&-12&4\\& & 6& 10& \color{black}{-4} \\ \hline &\color{blue}{3}&\color{blue}{5}&\color{blue}{-2}&\color{orangered}{0} \end{array} $$The solution is:
$$ \dfrac{ 3x^{3}-x^{2}-12x+4 }{ x-2 } = \color{blue}{3x^{2}+5x-2} $$Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x -2 = 0 $ ( $ x = \color{blue}{ 2 } $ ) at the left.
$$ \begin{array}{c|rrrr}\color{blue}{2}&3&-1&-12&4\\& & & & \\ \hline &&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrr}2&\color{orangered}{ 3 }&-1&-12&4\\& & & & \\ \hline &\color{orangered}{3}&&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 2 } \cdot \color{blue}{ 3 } = \color{blue}{ 6 } $.
$$ \begin{array}{c|rrrr}\color{blue}{2}&3&-1&-12&4\\& & \color{blue}{6} & & \\ \hline &\color{blue}{3}&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ -1 } + \color{orangered}{ 6 } = \color{orangered}{ 5 } $
$$ \begin{array}{c|rrrr}2&3&\color{orangered}{ -1 }&-12&4\\& & \color{orangered}{6} & & \\ \hline &3&\color{orangered}{5}&& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 2 } \cdot \color{blue}{ 5 } = \color{blue}{ 10 } $.
$$ \begin{array}{c|rrrr}\color{blue}{2}&3&-1&-12&4\\& & 6& \color{blue}{10} & \\ \hline &3&\color{blue}{5}&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -12 } + \color{orangered}{ 10 } = \color{orangered}{ -2 } $
$$ \begin{array}{c|rrrr}2&3&-1&\color{orangered}{ -12 }&4\\& & 6& \color{orangered}{10} & \\ \hline &3&5&\color{orangered}{-2}& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 2 } \cdot \color{blue}{ \left( -2 \right) } = \color{blue}{ -4 } $.
$$ \begin{array}{c|rrrr}\color{blue}{2}&3&-1&-12&4\\& & 6& 10& \color{blue}{-4} \\ \hline &3&5&\color{blue}{-2}& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ 4 } + \color{orangered}{ \left( -4 \right) } = \color{orangered}{ 0 } $
$$ \begin{array}{c|rrrr}2&3&-1&-12&\color{orangered}{ 4 }\\& & 6& 10& \color{orangered}{-4} \\ \hline &\color{blue}{3}&\color{blue}{5}&\color{blue}{-2}&\color{orangered}{0} \end{array} $$Bottom line represents the quotient $ \color{blue}{ 3x^{2}+5x-2 } $ with a remainder of $ \color{red}{ 0 } $.