The Horizontal Line Test is used to determine if the inverse of a function will also be a function.

To apply the Horizontal Line Test:

• If every horizontal line drawn across the graph of the function intersects the graph at most once, then the function is one-to-one, meaning its inverse will also be a function.
• If any horizontal line intersects the graph at more than one point, the function is not one-to-one, and therefore, its inverse will not be a function.

This test is crucial because, for a function to have an inverse that is also a function, it must be one-to-one.

Would you like further details or have any other questions?

Here are 5 related questions:

1. What is the Vertical Line Test used for?
2. Can a function have an inverse if it fails the Horizontal Line Test?
3. How do you algebraically verify if a function is one-to-one?
4. What is the relationship between injective functions and one-to-one functions?
5. How can you graphically represent the inverse of a function?

Tip: A function’s inverse essentially “undoes” the operation of the original function. For example, if $f(x) = y$, then $f^{-1}(y) = x$.