Perkalian Aljabar
\((x + p)(y + q) = \color{red}xy\color{black} +\color{red}xq\color{black}+ \color{blue}py\color{black}+\color{blue}pq\color{black}\)
Contoh 1
Jabarkan \((x + 5)(x + 9)\)
\begin{equation*}
\begin{split}
(x + 5)(x + 9)&= x\cdot x + x\cdot 9 + 5\cdot x + 5 \cdot 9\\\\
(x + 5)(x + 9)&= x^2 + 9x + 5x + 45\\\\
(x + 5)(x + 9)&= x^2 + 14x + 45
\end{split}
\end{equation*}
Contoh 2
Jabarkan \((2x - 5y)(x + 3y)\)
\begin{equation*}
\begin{split}
(2x - 5y)(x + 3y)&= 2x\cdot x + 2x\cdot 3y -5y\cdot x -5y \cdot 3y\\\\
(2x - 5y)(x + 3y)&= 2x^2 + 6xy -5xy -15y^2\\\\
(2x - 5y)(x + 3y)&= 2x^2 + xy -15y^2
\end{split}
\end{equation*}