Is x=|y| with inputs x=1, x=2, and x=3 a function? Explain

This is not a function

Explanation:

If x = 1, then,

x = |y|

1 = |y|

|y| = 1

y = plus/minus 1

y = 1 or y = -1

The input x = 1 leads to more than one output y = 1 and y = -1 at the same time.

Similar situations occur with x = 2 and x = 3.

This means we do not have a function. A function can only be possible if each input leads to exactly one output.