The solution to question number 10, $(\sqrt{5} - 3)(\sqrt{5} + 3)$, simplifies to $-4$.

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Here are five related questions to expand on this concept:

1. How do you simplify expressions with square roots and binomials?
2. What is the general formula for simplifying $(a - b)(a + b)$?
3. Can this method be used with complex numbers?
4. How do you handle higher powers of square roots in such expressions?
5. Can we apply a similar method for irrational or decimal values?

Tip: When simplifying $(a - b)(a + b)$, use the difference of squares formula: $a^2 - b^2$.