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