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Answer :

Answer:

Step-by-step explanation:

A function is one-to-one if it passes the horizontal line test.  This is the case if a horizontal line intersects the graph in only one place.  

The graph of f(x) = x^2 - 5 is that of a parabola that opens upward.  There are several possibilities here:

1.  The horizontal line intersects the parabolic graph twice on the interval (-infinity,+infinity).  Therefore this function is not one-to-one on this interval

(-infinity,+infinity).

2. If we define the domain as [0,+infinity), a horizontal line will intersect this parabolic graph only once.  Therefore this function is one-to-one on [0,+infinity).