Horizontal Line Test
- Irina Boyadzhiev
This applet can be used to determine whether a function is one-to-one or not, and also to restrict the domain to some interval where the function is one-to-one.
- Enter a function of x in the input box. Drag the vertical slider up or down (or press the Play button) to find the intersecting points of the graph and the horizontal line. To see the x-coordinates of the intersection points, check the “show coordinates”.
- Drag the left and/or the right side of the blue segment under the graph to restrict the domain.