Step 1: Write second polynomial below the first one. Making sure like terms are lined up.

$$ \begin{array}{lrrrr} & 20x^5 & 16x^3 & -4x^2 & \\ \color{red}{ - } & 9x^5 & & 3x^2 & 4 \\ \hline \end{array} $$

Step 2: Change ALL the signs in the second row.

$$ \begin{array}{lrrrr} & 20x^5 & 16x^3 & -4x^2 & \\ \color{red}{ - } & -9x^5 & & -3x^2 & -4 \\ \hline \end{array} $$

Step 3: Combine like terms (add each column):

$$ \begin{array}{lrrrr} & 20x^5 & 16x^3 & -4x^2 & \\ \color{red}{ - } & -9x^5 & & -3x^2 & -4 \\ \hline & 29x^5 & 16x^3 & -x^2 & 4 \end{array} $$

Polynomial Operations Calculator