Divide using synthetic division $$ ( 4x^{2}-10x-12 ) \div ( x-3 ) $$
Answer
The synthetic division table is:
$$ \begin{array}{c|rrr}3&4&-10&-12\\& & 12& \color{black}{6} \\ \hline &\color{blue}{4}&\color{blue}{2}&\color{orangered}{-6} \end{array} $$The solution is:
$$ \frac{ 4x^{2}-10x-12 }{ x-3 } = \color{blue}{4x+2} \color{red}{~-~} \frac{ \color{red}{ 6 } }{ x-3 } $$Explanation
Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x -3 = 0 $ ( $ x = \color{blue}{ 3 } $ ) at the left.
$$ \begin{array}{c|rrr}\color{blue}{3}&4&-10&-12\\& & & \\ \hline &&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrr}3&\color{orangered}{ 4 }&-10&-12\\& & & \\ \hline &\color{orangered}{4}&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 3 } \cdot \color{blue}{ 4 } = \color{blue}{ 12 } $.
$$ \begin{array}{c|rrr}\color{blue}{3}&4&-10&-12\\& & \color{blue}{12} & \\ \hline &\color{blue}{4}&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ -10 } + \color{orangered}{ 12 } = \color{orangered}{ 2 } $
$$ \begin{array}{c|rrr}3&4&\color{orangered}{ -10 }&-12\\& & \color{orangered}{12} & \\ \hline &4&\color{orangered}{2}& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 3 } \cdot \color{blue}{ 2 } = \color{blue}{ 6 } $.
$$ \begin{array}{c|rrr}\color{blue}{3}&4&-10&-12\\& & 12& \color{blue}{6} \\ \hline &4&\color{blue}{2}& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -12 } + \color{orangered}{ 6 } = \color{orangered}{ -6 } $
$$ \begin{array}{c|rrr}3&4&-10&\color{orangered}{ -12 }\\& & 12& \color{orangered}{6} \\ \hline &\color{blue}{4}&\color{blue}{2}&\color{orangered}{-6} \end{array} $$Bottom line represents the quotient $ \color{blue}{ 4x+2 } $ with a remainder of $ \color{red}{ -6 } $.