Features
Section Openers
Every section begins with an outline of the key
concepts covered in the section. This serves as a
class planning resource for the instructor and
a study and review guide for the student.
Explorations
For selected topics, Explorations offer the opportunity
to discover calculus concepts before they are formally
introduced in the text, thus enhancing student under-
standing. This optional feature can be omitted at the
discretion of the instructor with no loss of continuity
in the coverage of the material.
Historical Notes
Integrated throughout the text, Historical Notes help
students grasp the basic mathematical foundations
of calculus.
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Essential Calculus offers a number of proven
pedagogical features developed by the Larson team
to promote student mastery of Calculus. In order to
streamline this version for faster paced courses, we
have moved some content to online resources, leaving
the essential course content presented in a variety of
ways to appeal to different learning styles, instructional
approaches, and course configurations.
EXPLORATION
Integrating a Radical Function
Up to this point in the text, you have
not evaluated the following integral.
From geometry, you should be able to
find the exact value of this integral—
what is it? Using numerical integra-
tion with Simpson’s Rule or the
Trapezoidal Rule, you can’t be sure
of the accuracy of the approximation.
Why?
Try finding the exact value using the
substitution
and
Does your answer agree with the
value you obtained using geometry?
dx cos
d
.
x sin
1
1
1 x
2
dx
ARCHIMEDES (287–212 B.C.)
Archimedes used the method of exhaustion to
derive formulas for the areas of ellipses,
parabolic segments, and sectors of a spiral.
He is considered to have been the greatest
applied mathematician of antiquity.
Mary Evans Picture Library
80
Section 2.1 The Derivative and the Tangent Line Problem
• Find the slope of the tangent line to a curve at a point.
• Use the limit definition to find the derivative of a function.
• Understand the relationship between differentiability and continuity.
The Tangent Line Problem
Calculus grew out of four major problems that European mathematicians were work-
ing on during the seventeenth century.
1. The tangent line problem (this section)
2. The velocity and acceleration problem (Sections 2.2 and 2.3)
3. The minimum and maximum problem (Section 3.1)
4. The area problem (Section 4.2)
Each problem involves the notion of a limit, and calculus can be introduced with any
of the four problems.
Although partial solutions to the tangent line problem were given by Pierre de
Fermat (1601–1665), René Descartes (1596–1650), Christian Huygens (1629–1695),
and Isaac Barrow (1630 –1677), credit for the first general solution is usually given to
Isaac Newton (1642–1727) and Gottfried Leibniz (1646–1716). Newton’s work on
this problem stemmed from his interest in optics and light refraction.
What does it mean to say that a line is tangent to a curve at a point? For a circle,
the tangent line at a point is the line that is perpendicular to the radial line at point
as shown in Figure 2.1.
For a general curve, however, the problem is more difficult. For example, how
would you define the tangent lines shown in Figure 2.2? You might say that a line is
tangent to a curve at a point if it touches, but does not cross, the curve at point
This definition would work for the first curve shown in Figure 2.2, but not for the
second. Or you might say that a line is tangent to a curve if the line touches or
intersects the curve at exactly one point. This definition would work for a circle but
not for more general curves, as the third curve in Figure 2.2 shows.
P.P
P,
P
x
P
y
Tangent line to a circle
Figure 2.1
y
x
P
y
= f(x)
y
x
P
y
= f(x)
y
Tangent line to a curve at a point
Figure 2.2
F
OR FURTHER INFORMATION For
more information on the crediting of
mathematical discoveries to the first
“discoverer,” see the article
“Mathematical Firsts—Who Done It?”
by Richard H. Williams and Roy D.
Mazzagatti in Mathematics Teacher.
To view this article, go to the website
www.matharticles.com.
2
Differentiation