Example6.3.20

Multiply \(\left( x+5 \right)\left( x^2-4x+6 \right)\text{.}\)

We can approach this product using either distribution generic rectangles. We cannot directly use the FOIL method, although it can be helpful to draw arrows to the six pairs of products that will occur.

Using the distributive property, we begin by distributing across \(\left( x^2-4x+6 \right)\text{,}\) perform a second step of distribution, and then combine like terms.

\begin{align*} \left(x+5\right)\highlight{\left( x^2-4x+6 \right)} \amp= x\highlight{\left( x^2-4x+6 \right)}+5\highlight{\left( x^2-4x+6 \right)}\\ \amp= x\cdot x^2 - x\cdot 4x +x\cdot 6 +5\cdot x^2 - 5\cdot 4x +5\cdot 6\\ \amp= x^3 -4x^2 +6x +5x^2 -20x +30 \\ \amp= x^3+x^2-14x+30 \end{align*}
in-context