Question
Subtract polynomials: $ \, \color{blue}{ 4r^2-4r-8 } \, $ , $ \, \color{orangered}{ 9r^3-5r^2-9r+7 }$.
Answer
$$ \left( \color{blue}{4r^2-4r-8} \right) - \left( \color{orangered}{9r^3-5r^2-9r+7} \right) = -9r^3+9r^2+5r-15 $$
Explanation
Step 1: Write second polynomial below the first one. Making sure like terms are lined up.
$$ \begin{array}{lrrrr} & & 4r^2 & -4r & -8 \\ \color{red}{ - } & 9r^3 & -5r^2 & -9r & 7 \\ \hline \end{array} $$Step 2: Change ALL the signs in the second row.
$$ \begin{array}{lrrrr} & & 4r^2 & -4r & -8 \\ \color{red}{ - } & -9r^3 & 5r^2 & 9r & -7 \\ \hline \end{array} $$Step 3: Combine like terms (add each column):
$$ \begin{array}{lrrrr} & & 4r^2 & -4r & -8 \\ \color{red}{ - } & -9r^3 & 5r^2 & 9r & -7 \\ \hline & 9r^3 & -r^2 & -13r & -1 \end{array} $$This page was created using
Polynomial Operations Calculator