Why is $P[W \geq x]$, $W$ ~ $X^2(1)$ equal to $P(|Z| \geq \sqrt{x}), Z$ ~ $G(0,1)$

Question

My textbook (statistics) says this as part of a larger example:

= $P(W \geq x)$, $W$ ~ $X^2(1)$

= $P(|Z| \geq \sqrt{x}), Z$ ~ $G(0,1)$

I understand that $X^2(1)$ ~ $G(0,1)^2$ for large enough values of $n$, so we square root both sides to get $Z$ and $\sqrt{x}$, but where do the absolute signs come from in the 2nd equation?