Exercise 19.  Show   .  

Solution 19.

See text and/or instructor's solution manual.

By inequality (1-24), we see that  

        ,  

and also that ,  so that

        .

Putting these two inequalities together gives

        ,  

from whence the conclusion    follows.

This solution is complements of the authors.

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