Calculus I 
Quiz # 8

November 8, 2002

Name____________________ 
R. Hammack

Score ______

(1) The following function is onetoone. Find its inverse.
(2) The graph of a onetoone function f(x)
is drawn. Sketch the graph of .
Reflecting across the line y = x (dashed) gives the graph of
(sketched in red).
(3) Decide if the following functions are invertible. Explain your reasoning.
(a)
You know how to graph this function from Chapter 1.
First start with the graph of y =  x  , drawn in green.
Next graph y =  x  2 , drawn in orange.
Finally, graph of y =  x  2  + 3, is the orange graph moved up 3 units.
You can see that f (x) fails the horizontal line test, so it's not invertible.
(b)
Note that is
positive for any value of x because cos(x) can get no smaller than
1, and the other terms add up to more than 10. Hence, we conclude that the graph
of the function f(x) always increases, and never decreases. Therefore
it must pass the horizontal line test. Thus f(x)
is invertible.