Final Exam - Duke Mathematics Department

Math 201 Fall 2006
Final Exam
Name:__________________________________________________
You may use three sheets of notes and your calculator on this exam. Show all work, and work
carefully. You must turn in your sheets of notes with this exam.
1. In The Mathematical Universe, William Dunham writes, “At the heart of differential calculus
are the notions of slope … and tangent.” Describe how these two notions are used to define the
derivative of a function.
2. Consider the following data regarding the behavior of f(x). Note that you may need to use
values of x not listed in the table.
x
-5
-4
-3
-2
-1
0
1
2
3
4
5
f (x)
0
32
42
36
20
0
-18
-28
-24
0
50
f (x )
45
20
1
-12
-19
-20
-15
-4
13
36
65
f (x)
-28
-22
-16
-10
-4
2
8
14
20
26
32
(a) List all the locations x where f(x) has a local minimum.
(b) List all the locations x where f(x) has a local maximum.
(c) List all the locations x where f(x) has an inflection point.
(d) Is f(x) increasing or decreasing at x  3 ?
(e) Is f(x) concave up or concave down at x  2 ?
3. Name that rule! Next to each description, write the letter of the formula that corresponds to
it. Then give the name of the rule.
Description
Formula
New value = old value + slope*run
New guess = place where tangent line crosses the t-axis
First*derivative of second + second*derivative of first
Derivative of outside function*derivative of inside function
(a) [ f ( g (t ))]  f ( g (t )) g (t )
(b) y k 1  y k 
dy
t
dt
(c) ( fg )  fg   gf 
(d) t k 1  t k 
f (t k )
f (t k )
Name
4. The curve shown below, x 3  y 3  6xy, is called the folium of Descartes. Find an equation of
the line tangent to the curve at the point (3,3).
5. You know how to solve two of the following initial value problems exactly; the other you do not, but
you can solve it approximately. Solve the two you know how to solve. For the other, use Euler’s Method
with t  0.5 to estimate y at t  1 .
(a)
dy
 10  5 y
dt
y  3 at t  0
(b)
dy
 10  5t 2
dt
y  3 at t  0
(c)
dy
 10  5 y 2
dt
y  3 at t  0
6. Find the derivative of each of the following functions:
5  e 4t
____________________________________________
t 3  2e 7t
____________________________________________
6t 4  4t 3  7
____________________________________________
ln( 3 x)
____________________________________________
( x ln x  1) 3 / 2
____________________________________________
et
t
____________________________________________
3x 2  1
____________________________________________
e t cos t
____________________________________________
sin 3x
____________________________________________
3
t 5
____________________________________________
2
7. (a) When a raindrop falls from the sky, does its velocity remain constant? Explain briefly. Use a
differential equation to describe what is going on. Sketch a graph of its velocity over time.
(b) When you take a pan of Christmas cookies out of the oven, what happens to the temperature of the
cookies? Why? Sketch a graph of the temperature of the cookies as time goes by.
8. We are trying to find the zeros of the function below. Our first guess is that there is a root at
t  1 . Explain how Newton’s Method would find the next guess. Draw a picture to illustrate
your explanation. Label the next guess on the graph. Is it closer?
Extra Credit: 1 point each
Identify each mathematician (you may have to use the same person’s name more than once).
a. The two discoverers of calculus.
b. She was a Russian mathematician whose room was wallpapered with her father’s
calculus notes; she taught herself trigonometry.
c. He wrote about analytic geometry in an appendix to Discours de la Methode, but
his account was very difficult to read. The Cartesian plane is named after him.
d. These two scientists began to ask how things happen, not why they happen,
breaking the grip of Aristotelian thinking on science.
e. He wrote “A New Method for Maxima and Minima, as well as Tangents, which is
impeded neither by Fractional nor Irrational Quantities, and a Remarkable Type
of Calculus for This,” in a 1684 issue of Acta Eruditorum; this was the first
published account of calculus.
f. The doctrine of the followers of this man can be paraphrased as “All is number.”
Have a nice semester break!