Answer
$y=2|x|$ is not one-to-one.
Work Step by Step
*Condition for One-to-one Function (the Horizontal Line Test): The graph of function $y=f(x)$ intersects each horizontal line at most once.
Looking at the graph of $y=2|x|$, we notice that if we draw a horizontal line, it would intersect with our graph more than once.
In fact, I tried drawing a horizontal line $y=0.5$. From the image below, you can see that $y=0.5$ intersects our given graph at $2$ points.
Therefore, we conclude that $y=2|x|$ is not one-to-one.
