Find remainder when $ x^{3}-11x^{2}+36x-48 $ is divided by $ x-2 $.
Answer
The synthetic division table is:
$$ \begin{array}{c|rrrr}2&1&-11&36&-48\\& & 2& -18& \color{black}{36} \\ \hline &\color{blue}{1}&\color{blue}{-9}&\color{blue}{18}&\color{orangered}{-12} \end{array} $$The remainder when $ x^{3}-11x^{2}+36x-48 $ is divided by $ x-2 $ is $ \, \color{red}{ -12 } $.
Explanation
We can find remainder using synthetic division method.
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.
$$ \begin{array}{c|rrrr}\color{blue}{2}&1&-11&36&-48\\& & & & \\ \hline &&&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrrr}2&\color{orangered}{ 1 }&-11&36&-48\\& & & & \\ \hline &\color{orangered}{1}&&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 2 } \cdot \color{blue}{ 1 } = \color{blue}{ 2 } $.
$$ \begin{array}{c|rrrr}\color{blue}{2}&1&-11&36&-48\\& & \color{blue}{2} & & \\ \hline &\color{blue}{1}&&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ -11 } + \color{orangered}{ 2 } = \color{orangered}{ -9 } $
$$ \begin{array}{c|rrrr}2&1&\color{orangered}{ -11 }&36&-48\\& & \color{orangered}{2} & & \\ \hline &1&\color{orangered}{-9}&& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 2 } \cdot \color{blue}{ \left( -9 \right) } = \color{blue}{ -18 } $.
$$ \begin{array}{c|rrrr}\color{blue}{2}&1&-11&36&-48\\& & 2& \color{blue}{-18} & \\ \hline &1&\color{blue}{-9}&& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ 36 } + \color{orangered}{ \left( -18 \right) } = \color{orangered}{ 18 } $
$$ \begin{array}{c|rrrr}2&1&-11&\color{orangered}{ 36 }&-48\\& & 2& \color{orangered}{-18} & \\ \hline &1&-9&\color{orangered}{18}& \end{array} $$Step 6 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 2 } \cdot \color{blue}{ 18 } = \color{blue}{ 36 } $.
$$ \begin{array}{c|rrrr}\color{blue}{2}&1&-11&36&-48\\& & 2& -18& \color{blue}{36} \\ \hline &1&-9&\color{blue}{18}& \end{array} $$Step 7 : Add down last column: $ \color{orangered}{ -48 } + \color{orangered}{ 36 } = \color{orangered}{ -12 } $
$$ \begin{array}{c|rrrr}2&1&-11&36&\color{orangered}{ -48 }\\& & 2& -18& \color{orangered}{36} \\ \hline &\color{blue}{1}&\color{blue}{-9}&\color{blue}{18}&\color{orangered}{-12} \end{array} $$Remainder is the last entry in the bottom row $ \left(\color{red}{ -12 }\right) $.