Divide using synthetic division $$ ( x^{4}+8x^{2}+18x-24 ) \div ( x+3 ) $$
Answer
The synthetic division table is:
$$ \begin{array}{c|rrrrr}-3&1&0&8&18&-24\\& & -3& 9& -51& \color{black}{99} \\ \hline &\color{blue}{1}&\color{blue}{-3}&\color{blue}{17}&\color{blue}{-33}&\color{orangered}{75} \end{array} $$The solution is:
$$ \frac{ x^{4}+8x^{2}+18x-24 }{ x+3 } = \color{blue}{x^{3}-3x^{2}+17x-33} ~+~ \frac{ \color{red}{ 75 } }{ x+3 } $$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.
$$ \begin{array}{c|rrrrr}\color{blue}{-3}&1&0&8&18&-24\\& & & & & \\ \hline &&&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrrr}-3&\color{orangered}{ 1 }&0&8&18&-24\\& & & & & \\ \hline &\color{orangered}{1}&&&& \end{array} $$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 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-3}&1&0&8&18&-24\\& & \color{blue}{-3} & & & \\ \hline &\color{blue}{1}&&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ 0 } + \color{orangered}{ \left( -3 \right) } = \color{orangered}{ -3 } $
$$ \begin{array}{c|rrrrr}-3&1&\color{orangered}{ 0 }&8&18&-24\\& & \color{orangered}{-3} & & & \\ \hline &1&\color{orangered}{-3}&&& \end{array} $$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 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-3}&1&0&8&18&-24\\& & -3& \color{blue}{9} & & \\ \hline &1&\color{blue}{-3}&&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ 8 } + \color{orangered}{ 9 } = \color{orangered}{ 17 } $
$$ \begin{array}{c|rrrrr}-3&1&0&\color{orangered}{ 8 }&18&-24\\& & -3& \color{orangered}{9} & & \\ \hline &1&-3&\color{orangered}{17}&& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ 17 } = \color{blue}{ -51 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-3}&1&0&8&18&-24\\& & -3& 9& \color{blue}{-51} & \\ \hline &1&-3&\color{blue}{17}&& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ 18 } + \color{orangered}{ \left( -51 \right) } = \color{orangered}{ -33 } $
$$ \begin{array}{c|rrrrr}-3&1&0&8&\color{orangered}{ 18 }&-24\\& & -3& 9& \color{orangered}{-51} & \\ \hline &1&-3&17&\color{orangered}{-33}& \end{array} $$Step 8 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ \left( -33 \right) } = \color{blue}{ 99 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-3}&1&0&8&18&-24\\& & -3& 9& -51& \color{blue}{99} \\ \hline &1&-3&17&\color{blue}{-33}& \end{array} $$Step 9 : Add down last column: $ \color{orangered}{ -24 } + \color{orangered}{ 99 } = \color{orangered}{ 75 } $
$$ \begin{array}{c|rrrrr}-3&1&0&8&18&\color{orangered}{ -24 }\\& & -3& 9& -51& \color{orangered}{99} \\ \hline &\color{blue}{1}&\color{blue}{-3}&\color{blue}{17}&\color{blue}{-33}&\color{orangered}{75} \end{array} $$Bottom line represents the quotient $ \color{blue}{ x^{3}-3x^{2}+17x-33 } $ with a remainder of $ \color{red}{ 75 } $.