Divide using synthetic division $$ ( x^{5}-3x^{3}+2x ) \div ( x+3 ) $$
Answer
The synthetic division table is:
$$ \begin{array}{c|rrrrrr}-3&1&0&-3&0&2&0\\& & -3& 9& -18& 54& \color{black}{-168} \\ \hline &\color{blue}{1}&\color{blue}{-3}&\color{blue}{6}&\color{blue}{-18}&\color{blue}{56}&\color{orangered}{-168} \end{array} $$The solution is:
$$ \frac{ x^{5}-3x^{3}+2x }{ x+3 } = \color{blue}{x^{4}-3x^{3}+6x^{2}-18x+56} \color{red}{~-~} \frac{ \color{red}{ 168 } }{ x+3 } $$Explanation
Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x + 3 = 0 $ ( $ x = \color{blue}{ -3 } $ ) at the left.
$$ \begin{array}{c|rrrrrr}\color{blue}{-3}&1&0&-3&0&2&0\\& & & & & & \\ \hline &&&&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrrrr}-3&\color{orangered}{ 1 }&0&-3&0&2&0\\& & & & & & \\ \hline &\color{orangered}{1}&&&&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ 1 } = \color{blue}{ -3 } $.
$$ \begin{array}{c|rrrrrr}\color{blue}{-3}&1&0&-3&0&2&0\\& & \color{blue}{-3} & & & & \\ \hline &\color{blue}{1}&&&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ 0 } + \color{orangered}{ \left( -3 \right) } = \color{orangered}{ -3 } $
$$ \begin{array}{c|rrrrrr}-3&1&\color{orangered}{ 0 }&-3&0&2&0\\& & \color{orangered}{-3} & & & & \\ \hline &1&\color{orangered}{-3}&&&& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ \left( -3 \right) } = \color{blue}{ 9 } $.
$$ \begin{array}{c|rrrrrr}\color{blue}{-3}&1&0&-3&0&2&0\\& & -3& \color{blue}{9} & & & \\ \hline &1&\color{blue}{-3}&&&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -3 } + \color{orangered}{ 9 } = \color{orangered}{ 6 } $
$$ \begin{array}{c|rrrrrr}-3&1&0&\color{orangered}{ -3 }&0&2&0\\& & -3& \color{orangered}{9} & & & \\ \hline &1&-3&\color{orangered}{6}&&& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ 6 } = \color{blue}{ -18 } $.
$$ \begin{array}{c|rrrrrr}\color{blue}{-3}&1&0&-3&0&2&0\\& & -3& 9& \color{blue}{-18} & & \\ \hline &1&-3&\color{blue}{6}&&& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ 0 } + \color{orangered}{ \left( -18 \right) } = \color{orangered}{ -18 } $
$$ \begin{array}{c|rrrrrr}-3&1&0&-3&\color{orangered}{ 0 }&2&0\\& & -3& 9& \color{orangered}{-18} & & \\ \hline &1&-3&6&\color{orangered}{-18}&& \end{array} $$Step 8 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ \left( -18 \right) } = \color{blue}{ 54 } $.
$$ \begin{array}{c|rrrrrr}\color{blue}{-3}&1&0&-3&0&2&0\\& & -3& 9& -18& \color{blue}{54} & \\ \hline &1&-3&6&\color{blue}{-18}&& \end{array} $$Step 9 : Add down last column: $ \color{orangered}{ 2 } + \color{orangered}{ 54 } = \color{orangered}{ 56 } $
$$ \begin{array}{c|rrrrrr}-3&1&0&-3&0&\color{orangered}{ 2 }&0\\& & -3& 9& -18& \color{orangered}{54} & \\ \hline &1&-3&6&-18&\color{orangered}{56}& \end{array} $$Step 10 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ 56 } = \color{blue}{ -168 } $.
$$ \begin{array}{c|rrrrrr}\color{blue}{-3}&1&0&-3&0&2&0\\& & -3& 9& -18& 54& \color{blue}{-168} \\ \hline &1&-3&6&-18&\color{blue}{56}& \end{array} $$Step 11 : Add down last column: $ \color{orangered}{ 0 } + \color{orangered}{ \left( -168 \right) } = \color{orangered}{ -168 } $
$$ \begin{array}{c|rrrrrr}-3&1&0&-3&0&2&\color{orangered}{ 0 }\\& & -3& 9& -18& 54& \color{orangered}{-168} \\ \hline &\color{blue}{1}&\color{blue}{-3}&\color{blue}{6}&\color{blue}{-18}&\color{blue}{56}&\color{orangered}{-168} \end{array} $$Bottom line represents the quotient $ \color{blue}{ x^{4}-3x^{3}+6x^{2}-18x+56 } $ with a remainder of $ \color{red}{ -168 } $.