Remeber the differences between the horizontal and vertical line tests:

Horizontal Line Test: This test checks if a function is one-to-one by ensuring no horizontal line intersects the graph more than once. A one-to-one function has an inverse because it maps each output back to exactly one input.

Vertical Line Test: This test confirms whether a set of points on a graph represents a function by checking if no vertical line intersects the graph more than once. It determines function-ness but not invertibility.