Question 232754
The vertical line test:

draw a vertical line through the graph if it intersects the graph more than once it is not a function

This is a function
{{{graph (300,300,-10,10,-10,10,x^2)}}}

say you have a graph like {{{x=y^2}}} which would have that U shape, but rotated 90 degrees, that would not be a function. hence my lacking ability to graph it.