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