Divide using synthetic division $$ ( x^{3}-16x^{2}+83x-140 ) \div ( x-4 ) $$
Answer
The synthetic division table is:
$$ \begin{array}{c|rrrr}4&1&-16&83&-140\\& & 4& -48& \color{black}{140} \\ \hline &\color{blue}{1}&\color{blue}{-12}&\color{blue}{35}&\color{orangered}{0} \end{array} $$The solution is:
$$ \frac{ x^{3}-16x^{2}+83x-140 }{ x-4 } = \color{blue}{x^{2}-12x+35} $$Explanation
Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x -4 = 0 $ ( $ x = \color{blue}{ 4 } $ ) at the left.
$$ \begin{array}{c|rrrr}\color{blue}{4}&1&-16&83&-140\\& & & & \\ \hline &&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrr}4&\color{orangered}{ 1 }&-16&83&-140\\& & & & \\ \hline &\color{orangered}{1}&&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 4 } \cdot \color{blue}{ 1 } = \color{blue}{ 4 } $.
$$ \begin{array}{c|rrrr}\color{blue}{4}&1&-16&83&-140\\& & \color{blue}{4} & & \\ \hline &\color{blue}{1}&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ -16 } + \color{orangered}{ 4 } = \color{orangered}{ -12 } $
$$ \begin{array}{c|rrrr}4&1&\color{orangered}{ -16 }&83&-140\\& & \color{orangered}{4} & & \\ \hline &1&\color{orangered}{-12}&& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 4 } \cdot \color{blue}{ \left( -12 \right) } = \color{blue}{ -48 } $.
$$ \begin{array}{c|rrrr}\color{blue}{4}&1&-16&83&-140\\& & 4& \color{blue}{-48} & \\ \hline &1&\color{blue}{-12}&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ 83 } + \color{orangered}{ \left( -48 \right) } = \color{orangered}{ 35 } $
$$ \begin{array}{c|rrrr}4&1&-16&\color{orangered}{ 83 }&-140\\& & 4& \color{orangered}{-48} & \\ \hline &1&-12&\color{orangered}{35}& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 4 } \cdot \color{blue}{ 35 } = \color{blue}{ 140 } $.
$$ \begin{array}{c|rrrr}\color{blue}{4}&1&-16&83&-140\\& & 4& -48& \color{blue}{140} \\ \hline &1&-12&\color{blue}{35}& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ -140 } + \color{orangered}{ 140 } = \color{orangered}{ 0 } $
$$ \begin{array}{c|rrrr}4&1&-16&83&\color{orangered}{ -140 }\\& & 4& -48& \color{orangered}{140} \\ \hline &\color{blue}{1}&\color{blue}{-12}&\color{blue}{35}&\color{orangered}{0} \end{array} $$Bottom line represents the quotient $ \color{blue}{ x^{2}-12x+35 } $ with a remainder of $ \color{red}{ 0 } $.