Calculus-Sec-4-2-Solution


 4.2   The Shape of a Graph            by SGLee - HSKim - JHLee

                                                                                                            http://youtu.be/SVOWADHlzV8

1-5. Find the local maximum and minimum values of . In addition, find the intervals on which  is increasing and decreasing,

      and the intervals of concavity and the inflection points, sketch a graph of .

 

1. .

http://matrix.skku.ac.kr/cal-lab/cal-4-2-1.html 

 

      

      

      

      (a) local maximum:  

           local minimum: 

      (b) increasing on 

           decreasing on 

      (c) inflection point at 

           concave down on 

           concave up on 




 2. 

http://matrix.skku.ac.kr/cal-lab/cal-4-2-2.html  

 

 

      (a) local minimum: 

      (b) increasing on 

           decreasing on 

      (c) inflection point at 

           concave down on 

           concave up on 
















3. .

 

      

      

      

      (a) local maximum: 

           local minimum: 

      (b) increasing on 

           decreasing on 

      (c) inflection point at 

           concave down on 

           concave up on 




To find local maximum and minimum, use the next sage code.




To find inflection points, we calculate the second derivative.




4. 

 

     (a) local maximum :  No

         local minimum : 

      (b) increasing on 

         decreasing on 

      (c) inflection point : No

         concave up on 










 5. 

http://matrix.skku.ac.kr/cal-lab/cal-4-2-5.html  

 

 

      (a) Maximum : 1, Minimum : 0

      (b) interval of increase : 

           interval of decrease : 

      (c) inflection point at  변곡점은 0.722, -0.722

           concave down on       










6-11. Find the inflection points of  In addition, find intervals in which the graph of  is concave upward or concave downward.

 

6. 

 

 

      (a) inflection point at 

      (b) concave down on 

           concave up on 

                              







7. 

 

      

      

      

      

      (a) inflection point at 

      (b) concave up on 

         concave down on 

                            




8. 

 

      (a) inflection point at 

      (b) concave down on 

           concave up on 




 9. 

http://matrix.skku.ac.kr/cal-lab/cal-4-2-9.html 

 

 

     (a) critical point at ,  inflection point at 

     (b) concave down on 

          concave up on .










10. 

 

      

      

      

      

      (a) inflection point at 

      (b) concave up on 

           concave down on 




11. 

 

 

      (a) inflection points :  and 

      (b) concave down on 

         concave up on 




12-15. Find the vertical and horizontal asymptotes of .

 

12. 

 

 

      

      vertical asymptote 

      

      horizontal asymptote 







13. 

http://matrix.skku.ac.kr/cal-lab/cal-4-2-13.html 

 

 

      vertical asymptote 

      horizontal asymptote 




14. 

 

      

      horizontal asymptote 







15. 

http://matrix.skku.ac.kr/cal-lab/cal-4-2-15.html  

 

 

      vertical asymptote : 

      horizontal asymptote : No




16-18. Sketch the graph of  using the following information.

       (a) Find the local maximum and minimum values of .

       (b) Find the intervals of increase or decrease.

       (c) Find the inflection points of  and intervals of concavity.

       (d) Find the vertical and horizontal asymptotes.

 

16. 

 

      (a) local maximum : No

            local minimum : No

      (b) decreasing on 

      (c) inflection point at 

           concave up on 

           concave down on 

      (d) vertical asymptote : 

           horizontal asymptote : 




17. 

 

 

      

      

      (a) local minimum at 

      (b) increasing on 

            decreasing on 

      (c) inflection point : No

            concave up on 

      (d) vertical asymptote: 

           horizontal asymptote: No

                                                 







18.  

 

       and 

         and ;     and 

      (a) local minimum at 

            local maximum : 

      (b) increasing on 

           decreasing on 

      (c) inflection point at 

         concave up on 

         concave down on 

      (d) vertical asymptote: No

           horizontal asymptote: 




19. Find all the values of a such  has  different roots.

 

      Let . Then will have one local maximum and one local minimum. There will be  roots if and only if the maximum is positive and the minimum is negative.

       and .

       

      

       

    Note that  and . Hence  has local maximum at  and local minimum at .  Therefore, if  there will be  roots.







20. Find the minimum constant  for which  for all real .

    http://math1.skku.ac.kr/home/pub/1040/

 

 

       

      

      

      

      

      local minimum at 

      

      Therefore, .







21. Find  so that  has two  inflection points at  and .


 

     

      

      

       and so 

       and so .










22. Let .

      (a) Find  and .

      (b) Find the vertical and horizontal asymptotes of .

      (c) Sketch the graph of  using (a) and (b).

 

 

     (a) 

         

      (b) 

         vertical asymptote 

         horizontal asymptote 

      (c)   

 

 

 

 

 

 

                                        







23. Let  and  be increasing functions. Prove that  is increasing function.

 

     For 

      

      Therefore,  is increasing.




24. Prove the Concavity Test.

 

      (a) By Increasing Test

      If  on an interval  then  is increasing on .

      So  is concave upward on .

      Part (b) is proved similarly.




 25. Use CAS to find  and  when .

http://matrix.skku.ac.kr/cal-lab/cal-4-2-25.html 

 

  




 26. Let . Find the local maximum, minimum values and inflection points of . Sketch the graph of .

http://matrix.skku.ac.kr/cal-lab/cal-4-2-26.html 

 

 

      local maximum : 

      local minimum : No

      inflection point :   










 27. Let . Find the local maximum, minimum values and inflection points of .

http://matrix.skku.ac.kr/cal-lab/cal-4-2-27.html 

 

 

      local maximum : 

      local minimum : No

      inflection point : 




                                    

 

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