How do you use the vertical line test to show $x = | y |$ $x=absy$ is a function?

Question

2211 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-06-05T23:46:11

$y$ $y$ is not a function of $x$ $x$ .

For example, the vertical line $x = 1$ $x = 1$ intersects the relation $x = | y |$ $x = abs(y)$ at two points:

$(1, 1)$ $(1, 1)$ and $(1, - 1)$ $(1, -1)$

So $y$ $y$ is not uniquely determined by $x$ $x$ .

How do you use the vertical line test to show x=|y|x=absy is a function?