The expression in the image is:

$b^2 - x^2 - 4x - 4$

Would you like to solve this for a particular variable (e.g., $x$), or perform another operation such as factoring or simplifying?

Let me know if you need details or have any questions.

Here are five related questions to expand this topic:

1. How do you factor a quadratic expression like this one?
2. How do you complete the square for expressions involving $x$?
3. Can this expression be rewritten in a standard form?
4. How can you find the roots of a quadratic equation using the quadratic formula?
5. What is the difference between solving for $x$ and simplifying an expression?

Tip: When working with quadratics, always check if it can be factored before using more complex methods like completing the square or the quadratic formula.