Divide using synthetic division $$ ( 3x^{4}-16x^{3}-7x^{2}+64x-20 ) \div ( x+2 ) $$
Answer
The synthetic division table is:
$$ \begin{array}{c|rrrrr}-2&3&-16&-7&64&-20\\& & -6& 44& -74& \color{black}{20} \\ \hline &\color{blue}{3}&\color{blue}{-22}&\color{blue}{37}&\color{blue}{-10}&\color{orangered}{0} \end{array} $$The solution is:
$$ \frac{ 3x^{4}-16x^{3}-7x^{2}+64x-20 }{ x+2 } = \color{blue}{3x^{3}-22x^{2}+37x-10} $$Explanation
Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x + 2 = 0 $ ( $ x = \color{blue}{ -2 } $ ) at the left.
$$ \begin{array}{c|rrrrr}\color{blue}{-2}&3&-16&-7&64&-20\\& & & & & \\ \hline &&&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrrr}-2&\color{orangered}{ 3 }&-16&-7&64&-20\\& & & & & \\ \hline &\color{orangered}{3}&&&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -2 } \cdot \color{blue}{ 3 } = \color{blue}{ -6 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-2}&3&-16&-7&64&-20\\& & \color{blue}{-6} & & & \\ \hline &\color{blue}{3}&&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ -16 } + \color{orangered}{ \left( -6 \right) } = \color{orangered}{ -22 } $
$$ \begin{array}{c|rrrrr}-2&3&\color{orangered}{ -16 }&-7&64&-20\\& & \color{orangered}{-6} & & & \\ \hline &3&\color{orangered}{-22}&&& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -2 } \cdot \color{blue}{ \left( -22 \right) } = \color{blue}{ 44 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-2}&3&-16&-7&64&-20\\& & -6& \color{blue}{44} & & \\ \hline &3&\color{blue}{-22}&&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -7 } + \color{orangered}{ 44 } = \color{orangered}{ 37 } $
$$ \begin{array}{c|rrrrr}-2&3&-16&\color{orangered}{ -7 }&64&-20\\& & -6& \color{orangered}{44} & & \\ \hline &3&-22&\color{orangered}{37}&& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -2 } \cdot \color{blue}{ 37 } = \color{blue}{ -74 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-2}&3&-16&-7&64&-20\\& & -6& 44& \color{blue}{-74} & \\ \hline &3&-22&\color{blue}{37}&& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ 64 } + \color{orangered}{ \left( -74 \right) } = \color{orangered}{ -10 } $
$$ \begin{array}{c|rrrrr}-2&3&-16&-7&\color{orangered}{ 64 }&-20\\& & -6& 44& \color{orangered}{-74} & \\ \hline &3&-22&37&\color{orangered}{-10}& \end{array} $$Step 8 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -2 } \cdot \color{blue}{ \left( -10 \right) } = \color{blue}{ 20 } $.
$$ \begin{array}{c|rrrrr}\color{blue}{-2}&3&-16&-7&64&-20\\& & -6& 44& -74& \color{blue}{20} \\ \hline &3&-22&37&\color{blue}{-10}& \end{array} $$Step 9 : Add down last column: $ \color{orangered}{ -20 } + \color{orangered}{ 20 } = \color{orangered}{ 0 } $
$$ \begin{array}{c|rrrrr}-2&3&-16&-7&64&\color{orangered}{ -20 }\\& & -6& 44& -74& \color{orangered}{20} \\ \hline &\color{blue}{3}&\color{blue}{-22}&\color{blue}{37}&\color{blue}{-10}&\color{orangered}{0} \end{array} $$Bottom line represents the quotient $ \color{blue}{ 3x^{3}-22x^{2}+37x-10 } $ with a remainder of $ \color{red}{ 0 } $.