When can a quadratic function have an inverse?

Question

anonymous · Answer

)   When can a quadratic function have an inverse? 

Answers available in ...
10Take this time to do your
best on this question.  
  A)
 When its range is restricted.  Eliminate Reactivate   
  B)
 When its domain is restricted.  Eliminate Reactivate   
   C)
 When all the x-values are greater than -1.  Eliminate Reactivate   
  D)
 When all the y-values are greater than -1.

anonymous · Answer

those are my options

anonymous · Answer

i like "take your time" 
but the answer is when you restrict the domain of the original function, you can force it to be one to one and therefore it will have an inverse

anonymous · Answer

for a simple example you could say 
$$f(x)=x^2,x\geq 0$$ then the inverse would be $$f^{-1}(x)=\sqrt{x}$$

parthkohli · Answer

You make me think I suck at math :|