The given expression is $(x^2 - y^2)(x + y)$.

First, recognize that $x^2 - y^2$ is a difference of squares, which can be factored as:

$x^2 - y^2 = (x - y)(x + y)$

So, the expression becomes:

$(x - y)(x + y)(x + y)$

This can be further simplified by combining the like terms:

$(x - y) \cdot (x + y)^2$

Thus, the fully simplified form of the expression is:

$(x - y) \cdot (x + y)^2$

Would you like more details or have any questions?

Here are some related questions:

1. What is the general formula for the difference of squares?
2. How do you expand and simplify $(x + y)^2$?
3. Can $(x - y) \cdot (x + y)^2$ be expanded further?
4. What are the steps to factor a polynomial completely?
5. How does the distributive property apply in polynomial multiplication?

Tip: When multiplying polynomials, always factor them as much as possible before combining like terms. This often simplifies the process.