In order to make the radical sign meaningful, the constant in the radical sign must be greater than or equal to 0.

So: (2 (x 2)+2a * x-a)-1>; =0;

Namely: 2 (x 2)+2a * x-a > =1;

So: the exponent x2+2a * x-a >; =0 is a constant;

Moreover, the x 2 coefficient is an integer, so this equation has only one solution at most.

That is, the discriminant of root (2a)2-4 *(a)

Finally, the solution of the equation about A is-1

That is a ∈.