Divide using synthetic division $$ ( x^{3}-3x^{2}-15x-18 ) \div ( 6 ) $$
Answer
The synthetic division table is:
$$ \begin{array}{c|rrrr}0&1&-3&-15&-18\\& & 0& 0& \color{black}{0} \\ \hline &\color{blue}{1}&\color{blue}{-3}&\color{blue}{-15}&\color{orangered}{-18} \end{array} $$The solution is:
$$ \frac{ x^{3}-3x^{2}-15x-18 }{ x } = \color{blue}{x^{2}-3x-15} \color{red}{~-~} \frac{ \color{red}{ 18 } }{ x } $$Explanation
Step 1 : Write down the coefficients of the dividend into division table.Put the zero at the left.
$$ \begin{array}{c|rrrr}\color{blue}{0}&1&-3&-15&-18\\& & & & \\ \hline &&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrr}0&\color{orangered}{ 1 }&-3&-15&-18\\& & & & \\ \hline &\color{orangered}{1}&&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 0 } \cdot \color{blue}{ 1 } = \color{blue}{ 0 } $.
$$ \begin{array}{c|rrrr}\color{blue}{0}&1&-3&-15&-18\\& & \color{blue}{0} & & \\ \hline &\color{blue}{1}&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ -3 } + \color{orangered}{ 0 } = \color{orangered}{ -3 } $
$$ \begin{array}{c|rrrr}0&1&\color{orangered}{ -3 }&-15&-18\\& & \color{orangered}{0} & & \\ \hline &1&\color{orangered}{-3}&& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 0 } \cdot \color{blue}{ \left( -3 \right) } = \color{blue}{ 0 } $.
$$ \begin{array}{c|rrrr}\color{blue}{0}&1&-3&-15&-18\\& & 0& \color{blue}{0} & \\ \hline &1&\color{blue}{-3}&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -15 } + \color{orangered}{ 0 } = \color{orangered}{ -15 } $
$$ \begin{array}{c|rrrr}0&1&-3&\color{orangered}{ -15 }&-18\\& & 0& \color{orangered}{0} & \\ \hline &1&-3&\color{orangered}{-15}& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 0 } \cdot \color{blue}{ \left( -15 \right) } = \color{blue}{ 0 } $.
$$ \begin{array}{c|rrrr}\color{blue}{0}&1&-3&-15&-18\\& & 0& 0& \color{blue}{0} \\ \hline &1&-3&\color{blue}{-15}& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ -18 } + \color{orangered}{ 0 } = \color{orangered}{ -18 } $
$$ \begin{array}{c|rrrr}0&1&-3&-15&\color{orangered}{ -18 }\\& & 0& 0& \color{orangered}{0} \\ \hline &\color{blue}{1}&\color{blue}{-3}&\color{blue}{-15}&\color{orangered}{-18} \end{array} $$Bottom line represents the quotient $ \color{blue}{ x^{2}-3x-15 } $ with a remainder of $ \color{red}{ -18 } $.