a $x \square-2 x^{2}-3=0$

Step 1 ：Given the equation: \(x \square - 2x^2 - 3 = 0\). Let's assume the missing operator is '+'.

Step 2 ：Simplify the equation: \(-x^2 - 3 = 0\).

Step 3 ：Identify the coefficients: \(a = -1\), \(b = 0\), and \(c = -3\).

Step 4 ：Calculate the discriminant: \(\Delta = b^2 - 4ac = 0^2 - 4(-1)(-3) = -12\).

Step 5 ：Since the discriminant is negative, there are no real roots. \(\boxed{\text{No real roots}}\)