Check if $ -x $ is a factor of $ x^{4}-32x^{2}-144 $.

The synthetic division table is:

$$ \begin{array}{c|rrrrr}0&1&0&-32&0&-144\\& & 0& 0& 0& \color{black}{0} \\ \hline &\color{blue}{1}&\color{blue}{0}&\color{blue}{-32}&\color{blue}{0}&\color{orangered}{-144} \end{array} $$

Because the remainder $ \left( \color{red}{ -144 } \right) $ is not zero, we conclude that the $ x $ is not a factor of $ x^{4}-32x^{2}-144$.

First we need to create a synthetic division table.

Step 1 : Write down the coefficients of the dividend into division table.Put the zero at the left.

$$ \begin{array}{c|rrrrr}\color{blue}{0}&1&0&-32&0&-144\\& & & & & \\ \hline &&&&& \end{array} $$

Step 1 : Bring down the leading coefficient to the bottom row.

$$ \begin{array}{c|rrrrr}0&\color{orangered}{ 1 }&0&-32&0&-144\\& & & & & \\ \hline &\color{orangered}{1}&&&& \end{array} $$

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 } $.

$$ \begin{array}{c|rrrrr}\color{blue}{0}&1&0&-32&0&-144\\& & \color{blue}{0} & & & \\ \hline &\color{blue}{1}&&&& \end{array} $$

Step 3 : Add down last column: $ \color{orangered}{ 0 } + \color{orangered}{ 0 } = \color{orangered}{ 0 } $

$$ \begin{array}{c|rrrrr}0&1&\color{orangered}{ 0 }&-32&0&-144\\& & \color{orangered}{0} & & & \\ \hline &1&\color{orangered}{0}&&& \end{array} $$

Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 0 } \cdot \color{blue}{ 0 } = \color{blue}{ 0 } $.

$$ \begin{array}{c|rrrrr}\color{blue}{0}&1&0&-32&0&-144\\& & 0& \color{blue}{0} & & \\ \hline &1&\color{blue}{0}&&& \end{array} $$

Step 5 : Add down last column: $ \color{orangered}{ -32 } + \color{orangered}{ 0 } = \color{orangered}{ -32 } $

$$ \begin{array}{c|rrrrr}0&1&0&\color{orangered}{ -32 }&0&-144\\& & 0& \color{orangered}{0} & & \\ \hline &1&0&\color{orangered}{-32}&& \end{array} $$

Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 0 } \cdot \color{blue}{ \left( -32 \right) } = \color{blue}{ 0 } $.

$$ \begin{array}{c|rrrrr}\color{blue}{0}&1&0&-32&0&-144\\& & 0& 0& \color{blue}{0} & \\ \hline &1&0&\color{blue}{-32}&& \end{array} $$

Step 7 : Add down last column: $ \color{orangered}{ 0 } + \color{orangered}{ 0 } = \color{orangered}{ 0 } $

$$ \begin{array}{c|rrrrr}0&1&0&-32&\color{orangered}{ 0 }&-144\\& & 0& 0& \color{orangered}{0} & \\ \hline &1&0&-32&\color{orangered}{0}& \end{array} $$

Step 8 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 0 } \cdot \color{blue}{ 0 } = \color{blue}{ 0 } $.

$$ \begin{array}{c|rrrrr}\color{blue}{0}&1&0&-32&0&-144\\& & 0& 0& 0& \color{blue}{0} \\ \hline &1&0&-32&\color{blue}{0}& \end{array} $$

Step 9 : Add down last column: $ \color{orangered}{ -144 } + \color{orangered}{ 0 } = \color{orangered}{ -144 } $

$$ \begin{array}{c|rrrrr}0&1&0&-32&0&\color{orangered}{ -144 }\\& & 0& 0& 0& \color{orangered}{0} \\ \hline &\color{blue}{1}&\color{blue}{0}&\color{blue}{-32}&\color{blue}{0}&\color{orangered}{-144} \end{array} $$

Remainder is the last entry in the bottom row $ \left(\color{red}{ -144 }\right)$.

Synthetic Division Calculator