The question is to expand and simplify the given expression $(x + 3)(x - 3)(2x + 1)$.

Let's break this down step by step:

Step 1: Expand the first two terms $(x + 3)(x - 3)$

$(x + 3)(x - 3) = x^2 - 9$ (This is the difference of squares formula: $(a + b)(a - b) = a^2 - b^2$).

Step 2: Multiply the result by $(2x + 1)$

Now multiply $(x^2 - 9)$ by $(2x + 1)$: $(x^2 - 9)(2x + 1)$

Use the distributive property: $= (x^2)(2x) + (x^2)(1) + (-9)(2x) + (-9)(1)$

Simplify each term: $= 2x^3 + x^2 - 18x - 9$

Final Answer:

$2x^3 + x^2 - 18x - 9$

Would you like a more detailed explanation of any step or help with similar problems? Let me know!

Here are 5 related questions you might find helpful:

1. How do you apply the distributive property to expand expressions?
2. What is the difference of squares formula and when do we use it?
3. How do you simplify expressions involving polynomials?
4. Can you explain how to handle higher-degree polynomials in expansions?
5. How do you check your answer when expanding and simplifying?

Tip: Always group like terms carefully to ensure nothing is missed in the final step of simplification!