The given problem asks to solve the equation $x^2 = 18$ and write the solutions using the $\pm$ notation when appropriate.

Step-by-step solution:

1. Start with the equation:
   $x^2 = 18$

2. Take the square root of both sides:
   $x = \pm \sqrt{18}$

3. Simplify $\sqrt{18}$:
   $\sqrt{18} = \sqrt{9 \times 2} = 3\sqrt{2}$

4. The solution is:
   $x = \pm 3\sqrt{2}$

So the correct answer is $x = \pm 3\sqrt{2}$.

None of the options exactly match this form, but the solution should be expressed with the $\pm$ notation, so the correct interpretation would be that the solution uses $\pm$ with $\sqrt{18}$ simplified to $3\sqrt{2}$.

Would you like more details on this?

Here are 5 related questions to deepen your understanding:

1. What is the process of simplifying square roots?
2. How do you handle square roots in quadratic equations?
3. What is the significance of the $\pm$ symbol in solutions?
4. Can all quadratic equations be solved using square roots?
5. How do you determine if a solution has no real solutions?

Tip: Always check if the square root can be simplified further by factoring out perfect squares.