Question

can someone explain to me what the vertical line test is? I tried looking it up but everything on google is way complicated

Answer 1

Yes.
The vertical line test is a test used to determine if a relation is a function.

If you want to know if a relation is a function, and you have the graph of the relation, you use the vertical line test to determine whether or not the relation is a function.
What you do is you scan the graph from left to right with a vertical line. If at any position, the vertical intersects more than one point on the graph, then the relation is NOT a function. For the relation to be a function, the vertical line can intersect at most one point on the curve.