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