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