inverse of quadratic functions

[kbrac]

I don't understand how to find the restriction of an inverse of a quadratic equation.

 

[Unknown008]

Are you aware that a function needs to be a one-one function to have an inverse? Do you know what is a one-one function?

 

[tkhunny]

Notice that you used the words "an inverse", rather than "the inverse".

This may suggest to you that you have more than one choice. What is it about a parabola that might suggest two posibilities?

Hint: Think "Symmetry".