What I'm really asking is if I get to a point in a calculation where I have $|x| = -4$, do I say
There is no solution for $x$
or do I say
There is no solution for $x ∈ ℝ$
What I'm really asking is if I get to a point in a calculation where I have $|x| = -4$, do I say
There is no solution for $x$
or do I say
There is no solution for $x ∈ ℝ$
Well, first of all, if it depends on where you are looking for the solution. It is true that there is no solution for $x\in\mathbb C$, but if the question starts with "Does there exist such $x\in\mathbb N$[...]", then I would still say "there is no solution in $\mathbb N$".