Question

What is the domain of y = √x^2-1?

Answer 1

X can be -1 or 1 for the square root to be 0 

The correct option is a

Answer 2

$y=\sqrt{x^2-1}\\\\The\ domain:\\\\x^2-1\geq0\ \ \ |+1\\\\x^2\geq1\iff x\geq1\ \vee\ x\leq-1\to|x|\geq1\\\\Answer:\ a.\ |x|\geq1$