How to solve $x^2≠-1$?

Question

How to solve $x^2≠-1$?

Is it $x≠±i$?

I have to calculate a domain of a function and I have this doubt.

Answer 1

Your question is too broad.

If your function, is a real function, which means that $x \in A \subseteq \mathbb R$, then the expression $x^2+1 \neq 0$ is true $\forall x \in \mathbb R$. But if your function, is a complex function, which means that $x \in B \subseteq \mathbb C$, then the expression follows as : $x^2 +1 \neq 0 \Leftrightarrow x \neq \pm i$, as you simply get the points that you need to exclude, such that your statement is true (or just reverse-solving the equality in other words).