Question

how can I tell if something is a function?

Answer 1

if the x values repeats then relation isn't a function example
\[\large\rm (\color{ReD}{2},3)(4,5)(\color{ReD}{2},6)(5,5)\]
for graph
draw a vertical line if the graph of the equation intersect the vertical line more more than one timez then relation isn't a function

Answer 2

would something like this be a function?

Answer 3

draw a vertical line
if the graph intersect vertical line more than one time then no

Answer 4

got it ??