To expand and simplify the expression $4(x + 3)$, you need to distribute the 4 across both terms inside the parentheses.

Here’s the step-by-step process:

1. Distribute the 4: $4(x + 3) = 4 \cdot x + 4 \cdot 3$

2. Simplify each term: $4x + 12$

Thus, the expanded and simplified expression is: $4x + 12$

Would you like more details on the steps or have any questions?

Here are 5 related questions you can explore:

1. How would you expand $3(x + 5)$?
2. What is the process to expand and simplify $5(2x - 4)$?
3. How do you factor $4x + 12$ back into a product?
4. Can you expand $4(x + y + 3)$?
5. How would you expand and simplify $4(x^2 + 3x + 2)$?

Tip: Always ensure you distribute to every term inside the parentheses when expanding expressions.