Exercise 17.  Suppose that either    or  .  Prove that  .

Solution 17.

See text and/or instructor's solution manual.

Use the general relationship

            

The special form for this problem is

          

Using the two relations given above we see that if   then we have

        ,  and  

        .

Thus  ,  and the conclusion follows.

Similarly, if we get the same result.

This solution is complements of the authors.

(c) 2008 John H. Mathews, Russell W. Howell