#### To determine

**To find:** f-16

#### Answer

f-16=4

#### Explanation

You can determine whether or not the given function is one to one by just looking at the graph with the help of Horizontal Line Test. Horizontal Line Test says that a function f is one to one if and only if any horizontal line intersects the graph of given function exactly at one point. In other words, the Horizontal Line Test can be stated as:

A function f is NOT one to one if and only if there exists a horizontal line which intersects the graph of given function at least at two point.

Any horizontal line will intersect the given graph exactly once. Therefore, by using the Horizontal Line test, we can conclude that the given function is one to one.

Now,

x=f−1(6)f(x)=f(f−1(6))x+x=6x=4 [x=4 is a perfect square]f−1(6)=4

The image for point 4 occurs at 6, i.e., f−1(4)=6 Also, by using the Horizontal Line Test, we can conclude that h is one to one, and,

**Conclusion:** Therefore,h-16=4.