The expression $(a + b)(a - b)$ represents the product of a sum and a difference, which is a classic difference of squares formula. It simplifies as follows:

$(a + b)(a - b) = a^2 - b^2$

So, $(a + b)(a - b) = a^2 - b^2$.

Would you like further explanation on this?

Here are some related questions to explore this topic further:

1. How does the difference of squares formula apply to specific values of $a$ and $b$?
2. Can the difference of squares be expanded to three terms, like $(a+b+c)(a-b-c)$?
3. What are some real-life applications of the difference of squares formula?
4. How does the difference of squares formula relate to factoring polynomials?
5. How can the difference of squares be visualized geometrically?

Tip: The difference of squares is often used to simplify expressions and solve equations, especially when factoring is involved.