Divide using synthetic division $$ ( x^{3}+4x^{2}-5x+4 ) \div ( x-8 ) $$
Answer
The synthetic division table is:
$$ \begin{array}{c|rrrr}8&1&4&-5&4\\& & 8& 96& \color{black}{728} \\ \hline &\color{blue}{1}&\color{blue}{12}&\color{blue}{91}&\color{orangered}{732} \end{array} $$The solution is:
$$ \frac{ x^{3}+4x^{2}-5x+4 }{ x-8 } = \color{blue}{x^{2}+12x+91} ~+~ \frac{ \color{red}{ 732 } }{ x-8 } $$Explanation
Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x -8 = 0 $ ( $ x = \color{blue}{ 8 } $ ) at the left.
$$ \begin{array}{c|rrrr}\color{blue}{8}&1&4&-5&4\\& & & & \\ \hline &&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrr}8&\color{orangered}{ 1 }&4&-5&4\\& & & & \\ \hline &\color{orangered}{1}&&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 8 } \cdot \color{blue}{ 1 } = \color{blue}{ 8 } $.
$$ \begin{array}{c|rrrr}\color{blue}{8}&1&4&-5&4\\& & \color{blue}{8} & & \\ \hline &\color{blue}{1}&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ 4 } + \color{orangered}{ 8 } = \color{orangered}{ 12 } $
$$ \begin{array}{c|rrrr}8&1&\color{orangered}{ 4 }&-5&4\\& & \color{orangered}{8} & & \\ \hline &1&\color{orangered}{12}&& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 8 } \cdot \color{blue}{ 12 } = \color{blue}{ 96 } $.
$$ \begin{array}{c|rrrr}\color{blue}{8}&1&4&-5&4\\& & 8& \color{blue}{96} & \\ \hline &1&\color{blue}{12}&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -5 } + \color{orangered}{ 96 } = \color{orangered}{ 91 } $
$$ \begin{array}{c|rrrr}8&1&4&\color{orangered}{ -5 }&4\\& & 8& \color{orangered}{96} & \\ \hline &1&12&\color{orangered}{91}& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 8 } \cdot \color{blue}{ 91 } = \color{blue}{ 728 } $.
$$ \begin{array}{c|rrrr}\color{blue}{8}&1&4&-5&4\\& & 8& 96& \color{blue}{728} \\ \hline &1&12&\color{blue}{91}& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ 4 } + \color{orangered}{ 728 } = \color{orangered}{ 732 } $
$$ \begin{array}{c|rrrr}8&1&4&-5&\color{orangered}{ 4 }\\& & 8& 96& \color{orangered}{728} \\ \hline &\color{blue}{1}&\color{blue}{12}&\color{blue}{91}&\color{orangered}{732} \end{array} $$Bottom line represents the quotient $ \color{blue}{ x^{2}+12x+91 } $ with a remainder of $ \color{red}{ 732 } $.