Answer
$$x^2-18$$
Work Step by Step
To write a quadratic equation with the given values as solutions, we find the corresponding factors. We then FOIL out the factors to find the original quadratic equation:
$$ \left(x-3\sqrt{2}\right)\left(x+3\sqrt{2}\right)\\ x^2-\left(3\sqrt{2}\right)^2\\ x^2-18$$