Learning Resources

Investigation 4: The Square-Root Function & Focus H: Irrational Functions and Inverses

Step B:

Take care to scale the axes equally or you will miss the fact that one graph is the reflection image of the other. If you are using technology, use the ZOOM feature and select option 5: ZSquare. 

You should notice that that square-root graph is half of the image of a parabola. This graph does indeed represent a function since it passes the Vertical Line Test. That is, any vertical line drawn intersects in exactly one point.