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