Solve \( x^{2}=18 \), where \( x \) is a real number. Simplify your answer as much as possible. If there is more than one solution, separate them with commas. If there is no solution, click "No solution." \( x=\square \)

To solve the equation \( x^{2} = 18 \), we start by taking the square root of both sides. This gives us: \[ x = \pm \sqrt{18}. \] Next, we can simplify \( \sqrt{18} \). It can be expressed as \( \sqrt{9 \times 2} = \sqrt{9} \times \sqrt{2} = 3\sqrt{2} \). Therefore, the solutions are: \[ x = 3\sqrt{2}, -3\sqrt{2}. \] So the final answer is: \( x = 3\sqrt{2}, -3\sqrt{2} \)