Math 2602

March 21 , 2000


Name:____________________________

Don't Panic

Open Book and Notes. You have 50 minutes. Carefully explain your proceedures and answers

[Graphics:Images/index_gr_1.gif]

Problem 1 (10 points)

Sum by converting to a difference equation and solving that difference equation:


Express
[Graphics:Images/index_gr_2.gif] as  a sum of falling factorials.


Use this result to find:

[Graphics:Images/index_gr_3.gif]

Answer
[Graphics:Images/index_gr_4.gif]
[Graphics:Images/index_gr_5.gif]

Problem  2 (10 Points)

Sum by parts:



[Graphics:Images/index_gr_6.gif]

Answer

[Graphics:Images/index_gr_7.gif]

Problem 3: (8 points)

Find the difference (with respect to n- 1 point each)



a)
[Graphics:Images/index_gr_8.gif]

[Graphics:Images/index_gr_9.gif]
[Graphics:Images/index_gr_10.gif]


   

b)  n!

[Graphics:Images/index_gr_11.gif]
[Graphics:Images/index_gr_12.gif]

Not what I was expecting, but correct.
        
        (n+1)! - n ! =
   (n+1) n! - n! = n n!



c)  [Graphics:Images/index_gr_13.gif]

[Graphics:Images/index_gr_14.gif]
[Graphics:Images/index_gr_15.gif]


d) [Graphics:Images/index_gr_16.gif]

[Graphics:Images/index_gr_17.gif]
[Graphics:Images/index_gr_18.gif]

Since [Graphics:Images/index_gr_19.gif] = [Graphics:Images/index_gr_20.gif] + [Graphics:Images/index_gr_21.gif], we get [Graphics:Images/index_gr_22.gif]  for the difference.


Find  an anti -difference: (with respect to n - 2 points each)

e) n(n!)

[Graphics:Images/index_gr_23.gif]



f) [Graphics:Images/index_gr_24.gif]

[Graphics:Images/index_gr_25.gif]


Converted by Mathematica      April 26, 2000