Question

multiply:
(4w + 5f)(4w - 5f)
(4w + 5f)(4w - 5f) = \square
(simplify your answer.)

Explanation:

Step1: Apply difference of squares rule

Recall the identity $(a+b)(a-b)=a^2-b^2$. Here, $a=4w$, $b=5f$.

Step2: Calculate $a^2$ and $b^2$

$a^2=(4w)^2=16w^2$, $b^2=(5f)^2=25f^2$

Step3: Substitute into the identity

$$\begin{align*} (4w+5f)(4w-5f)&=(4w)^2-(5f)^2\\ &=16w^2-25f^2 \end{align*}$$

Answer:

$16w^2 - 25f^2$