Homework, Page 335

Homework



Homework Assignment #4
Read Section 5.5
Page 335, Exercises: 1 – 49(EOO)
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
1.
Write the area function of f (x) = 2x + 4 with lower limit
a = –2 as an integral and find a formula for it.
x
2

 2 x  4  dx  F  x   F  2   x
2

 4 x   2   4  2 
2

 x2  4 x  4
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
 4
5. Find G 1 , G  0  , and G 
, where G  x   1 tan tdt
x
d x
G 1   tan tdt  0  G   x  
1 tan tdt  tan x
dx
1
1
 4   tan  4  1
G 1  0, G   0   0, G     1
4
G  0   tan 0  0, G 
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
Find formulas for the functions represented by the integrals.
x2
9. 1 tdt
2
 tdt  F  x   F 1 
x2
1
x
  1
2 2
2
2
x4 1

2
2
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
Find formulas for the functions represented by the integrals.
x
13.  sec2  d
4
x


4
 4
 tan x  tan      tan x  1
4
sec 2  d  F  x   F  
x


4
sec 2  d  tan x  1
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
Express the antiderivative F(x) of f (x) satisfying the given initial
condition as an integral.
17. sec x, F  0   0
F  x   0 sec tdt
x
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
Calculate the derivative.
d t
21.
100 cos 5 xdx
dt
d t
100 cos 5 xdx  cos 5t
dt
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
25.
Make a rough sketch of the graph of the area function of
g(x) shown in Figure 12.
1
2
3
4
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
Calculate the derivative.
d x2 2
29.
0 sin tdt
dx
d x2 2
2 2
2 2
sin
tdt

sin
x
2
x

2
x
sin
x


0
dx
d x2 2
2 2
0 sin tdt  2 x sin x
dx
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
Calculate the derivative.
d 0
2
33.
sin
tdt
3
x
dx
d 0
d x3 2
2
2 3
2
2
2 3
x3 sin tdt   0 sin tdt   sin x  3x   3x sin x
dx
dx
d 0
2
2
2 3
sin
tdt


3
x
sin
x
3
x
dx
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
Let A  x   0 f  t  dt and B  x   2 f  t  dt with f  x  as in Figure 13.
x
37.
x
Find the min and max of A(x) on [0, 6].
min  1.25, max  1.25
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
41.
Area Functions and Concavity. Explain why the
following statements are true. Assume f (x) is differentiable.
(a)
If c is an inflection point of A(x), then f ′(c) = 0.
Since f(x) = A′(x), f ′(x) =A″(x) and A″(x) = 0 at
inflections points of A(x).
(b)
A(x) is concave up if f (x) is increasing.
If f(x) is increasing, then f ′(x) > 0, hence A″(x) > 0 and
A(x) is concave up.
(c)
A(x) is concave down if f (x) is decreasing.
If f(x) is decreasing, then f ′(x) < 0, hence A″(x) < 0 and
A(x) is concave up.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
45.
Sketch the graph of an increasing function f (x) such that
both f ′(x) and A (x) are decreasing.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework, Page 335
49.
Determine the function g (x) and all values of c such that
2
g
t
dt

x
 x6



x
c
d 2
x  x  6  2x  1  g  x 

dx
x 2  x  6  0   x  2  x  3  0  c  3, 2
2 g  x   x  1, c  3, 2
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Jon Rogawski
Calculus, ET
First Edition
Chapter 5: The Integral
Section 5.5: Net or Total Change as the
Integral of a Rate
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
If water enters an empty bucket at the rate r(t), as shown in Figure 1,
then the amount of water in the bucket at any time on the interval [0, 4]
is equal to the area under the curve up to the vertical line at the time
in question.
Since the water enters the bucket at a varying rate, we can use
the FTC to find the amount of water in the bucket at any time x,
specifically: r  t  dt  R  x   R  0  . Since the bucket is initially
empty, the amount of water in the bucket is at time x is R( x) and the
integral gives us the net change in the amount of water in the bucket.
x
0
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
If s′(t) is both positive and negative on [t1, t2], the integral will total
the signed areas and give us the net change in s. This is the basis of
Theorem 1.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Example, Page 341
4.
A survey shows that a mayoral candidate is gaining votes
at the rate of 2000t + 1000 votes per day since she announced her
candidacy. How many supporters will the candidate have after
60 days, assuming she had no supporters at t = 0.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
The table shows the flow rate of cars passing an observation point in
units of cars per hour. Estimate the number of cars using the highway
in the two hour period by taking the average of the left and right
Riemann sums.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Remembering that displacement is a vector quantity, the integral of
velocity, another vector quantity, over an interval of time gives us the
net displacement. To find distance traveled, we must take the integral
of the absolute value of velocity, as illustrated in Figure 2.
Figure 3 illustrates
the path of the
particle with velocity
v(t) from Figure 2.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Theorem 2 formalizes what we observed in Figure 2.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Example, Page 341
8.
A projectile is released with initial vertical velocity 100
m/s. Use the formula v(t) = 100 – 9.8t for velocity to determine
distance traveled in the first 15 seconds.
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Example, Page 341
18.
Suppose that the marginal cost of producing x video
recorders is 0.001x2 – 0.6x + 350 dollars. What is the cost of
producing 300 units? If production is set at 300 units, what is the
cost of producing 20 additional units?
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company
Homework



Homework Assignment #5
Read Section 5.6
Page 341, Exercises: 1 – 19(Odd)
Rogawski Calculus
Copyright © 2008 W. H. Freeman and Company