1. Let's clarify the problem: You are asking why the answer is not simply positive or negative 3, as in option (d). 2. Typically, when solving equations like $x^2 = 9$, the solutions are $x = \pm 3$, meaning both positive 3 and negative 3 are valid. 3. However, sometimes the problem context or additional constraints restrict the solution to only one value. 4. For example, if the problem states $x = \sqrt{9}$, the square root symbol by definition returns only the principal (non-negative) root, which is 3. 5. So, if the problem uses the square root function explicitly, the answer is only positive 3, not negative 3. 6. If the problem is an equation like $x^2 = 9$, then both $x = 3$ and $x = -3$ are solutions. 7. Therefore, the reason the answer is not both positive and negative 3 depends on whether the problem is asking for the square root (only positive) or solving a quadratic equation (both positive and negative). 8. Always check the problem statement carefully to understand if the negative root is included or excluded. Final answer: The solution is not both positive and negative 3 if the problem involves the square root function, which returns only the positive root.