MA123, Chapter 6: Extreme Values, Mean Value
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Selected Solutions to Assignment #1 (With Corrections)
Math 310 Numerical Analysis, Fall 2010 (Bueler) September 23, 2010 Selected Solutions to Assignment #1 (with corrections) 2. Because the functions are continuous on the given intervals, we show these equations have solutions by checking that the functions have opposite signs at the ends of the given intervals, and then by invoking the Intermediate Value Theorem (IVT). a. f(0:2) = −0:28399 and f(0:3) = 0:0066009. Because f(x) is continuous on [0:2; 0:3], and because f has different signs at the ends of this interval, by the IVT there is a solution c in [0:2; 0:3] so that f(c) = 0. Similarly, for [1:2; 1:3] we see f(1:2) = 0:15483; f(1:3) = −0:13225. And etc. b. Again the function is continuous. For [1; 2] we note f(1) = 1 and f(2) = −0:69315. By the IVT there is a c in (1; 2) so that f(c) = 0. For the interval [e; 4], f(e) = −0:48407 and f(4) = 2:6137. And etc. 3. One of my purposes in assigning these was that you should recall the Extreme Value Theorem. It guarantees that these problems have a solution, and it gives an algorithm for finding it. That is, \search among the critical points and the endpoints." a. The discontinuities of this rational function are where the denominator is zero. But the solutions of x2 − 2x = 0 are at x = 2 and x = 0, so the function is continuous on the interval [0:5; 1] of interest. -
2.4 the Extreme Value Theorem and Some of Its Consequences
2.4 The Extreme Value Theorem and Some of its Consequences The Extreme Value Theorem deals with the question of when we can be sure that for a given function f , (1) the values f (x) don’t get too big or too small, (2) and f takes on both its absolute maximum value and absolute minimum value. We’ll see that it gives another important application of the idea of compactness. 1 / 17 Definition A real-valued function f is called bounded if the following holds: (∃m, M ∈ R)(∀x ∈ Df )[m ≤ f (x) ≤ M]. If in the above definition we only require the existence of M then we say f is upper bounded; and if we only require the existence of m then say that f is lower bounded. 2 / 17 Exercise Phrase boundedness using the terms supremum and infimum, that is, try to complete the sentences “f is upper bounded if and only if ...... ” “f is lower bounded if and only if ...... ” “f is bounded if and only if ...... ” using the words supremum and infimum somehow. 3 / 17 Some examples Exercise Give some examples (in pictures) of functions which illustrates various things: a) A function can be continuous but not bounded. b) A function can be continuous, but might not take on its supremum value, or not take on its infimum value. c) A function can be continuous, and does take on both its supremum value and its infimum value. d) A function can be discontinuous, but bounded. e) A function can be discontinuous on a closed bounded interval, and not take on its supremum or its infimum value. -
Circles Project
Circles Project C. Sormani, MTTI, Lehman College, CUNY MAT631, Fall 2009, Project X BACKGROUND: General Axioms, Half planes, Isosceles Triangles, Perpendicular Lines, Con- gruent Triangles, Parallel Postulate and Similar Triangles. DEFN: A circle of radius R about a point P in a plane is the collection of all points, X, in the plane such that the distance from X to P is R. That is, C(P; R) = fX : d(X; P ) = Rg: Note that a circle is a well defined notion in any metric space. We say P is the center and R is the radius. If d(P; Q) < R then we say Q is an interior point of the circle, and if d(P; Q) > R then Q is an exterior point of the circle. DEFN: The diameter of a circle C(P; R) is a line segment AB such that A; B 2 C(P; R) and the center P 2 AB. The length AB is also called the diameter. THEOREM: The diameter of a circle C(P; R) has length 2R. PROOF: Complete this proof using the definition of a line segment and the betweenness axioms. DEFN: If A; B 2 C(P; R) but P2 = AB then AB is called a chord. THEOREM: A chord of a circle C(P; R) has length < 2R unless it is the diameter. PROOF: Complete this proof using axioms and the above theorem. DEFN: A line L is said to be a tangent line to a circle, if L \ C(P; R) is a single point, Q. The point Q is called the point of contact and L is said to be tangent to the circle at Q. -
Continuous Functions, Smooth Functions and the Derivative C 2012 Yonatan Katznelson
ucsc supplementary notes ams/econ 11a Continuous Functions, Smooth Functions and the Derivative c 2012 Yonatan Katznelson 1. Continuous functions One of the things that economists like to do with mathematical models is to extrapolate the general behavior of an economic system, e.g., forecast future trends, from theoretical assumptions about the variables and functional relations involved. In other words, they would like to be able to tell what's going to happen next, based on what just happened; they would like to be able to make long term predictions; and they would like to be able to locate the extreme values of the functions they are studying, to name a few popular applications. Because of this, it is convenient to work with continuous functions. Definition 1. (i) The function y = f(x) is continuous at the point x0 if f(x0) is defined and (1.1) lim f(x) = f(x0): x!x0 (ii) The function f(x) is continuous in the interval (a; b) = fxja < x < bg, if f(x) is continuous at every point in that interval. Less formally, a function is continuous in the interval (a; b) if the graph of that function is a continuous (i.e., unbroken) line over that interval. Continuous functions are preferable to discontinuous functions for modeling economic behavior because continuous functions are more predictable. Imagine a function modeling the price of a stock over time. If that function were discontinuous at the point t0, then it would be impossible to use our knowledge of the function up to t0 to predict what will happen to the price of the stock after time t0. -
Two Fundamental Theorems About the Definite Integral
Two Fundamental Theorems about the Definite Integral These lecture notes develop the theorem Stewart calls The Fundamental Theorem of Calculus in section 5.3. The approach I use is slightly different than that used by Stewart, but is based on the same fundamental ideas. 1 The definite integral Recall that the expression b f(x) dx ∫a is called the definite integral of f(x) over the interval [a,b] and stands for the area underneath the curve y = f(x) over the interval [a,b] (with the understanding that areas above the x-axis are considered positive and the areas beneath the axis are considered negative). In today's lecture I am going to prove an important connection between the definite integral and the derivative and use that connection to compute the definite integral. The result that I am eventually going to prove sits at the end of a chain of earlier definitions and intermediate results. 2 Some important facts about continuous functions The first intermediate result we are going to have to prove along the way depends on some definitions and theorems concerning continuous functions. Here are those definitions and theorems. The definition of continuity A function f(x) is continuous at a point x = a if the following hold 1. f(a) exists 2. lim f(x) exists xœa 3. lim f(x) = f(a) xœa 1 A function f(x) is continuous in an interval [a,b] if it is continuous at every point in that interval. The extreme value theorem Let f(x) be a continuous function in an interval [a,b]. -
A Brief Summary of Math 125 the Derivative of a Function F Is Another
A Brief Summary of Math 125 The derivative of a function f is another function f 0 defined by f(v) − f(x) f(x + h) − f(x) f 0(x) = lim or (equivalently) f 0(x) = lim v!x v − x h!0 h for each value of x in the domain of f for which the limit exists. The number f 0(c) represents the slope of the graph y = f(x) at the point (c; f(c)). It also represents the rate of change of y with respect to x when x is near c. This interpretation of the derivative leads to applications that involve related rates, that is, related quantities that change with time. An equation for the tangent line to the curve y = f(x) when x = c is y − f(c) = f 0(c)(x − c). The normal line to the curve is the line that is perpendicular to the tangent line. Using the definition of the derivative, it is possible to establish the following derivative formulas. Other useful techniques involve implicit differentiation and logarithmic differentiation. d d d 1 xr = rxr−1; r 6= 0 sin x = cos x arcsin x = p dx dx dx 1 − x2 d 1 d d 1 ln jxj = cos x = − sin x arccos x = −p dx x dx dx 1 − x2 d d d 1 ex = ex tan x = sec2 x arctan x = dx dx dx 1 + x2 d 1 d d 1 log jxj = ; a > 0 cot x = − csc2 x arccot x = − dx a (ln a)x dx dx 1 + x2 d d d 1 ax = (ln a) ax; a > 0 sec x = sec x tan x arcsec x = p dx dx dx jxj x2 − 1 d d 1 csc x = − csc x cot x arccsc x = − p dx dx jxj x2 − 1 d product rule: F (x)G(x) = F (x)G0(x) + G(x)F 0(x) dx d F (x) G(x)F 0(x) − F (x)G0(x) d quotient rule: = chain rule: F G(x) = F 0G(x) G0(x) dx G(x) (G(x))2 dx Mean Value Theorem: If f is continuous on [a; b] and differentiable on (a; b), then there exists a number f(b) − f(a) c in (a; b) such that f 0(c) = . -
Chapter 12 Applications of the Derivative
Chapter 12 Applications of the Derivative Now you must start simplifying all your derivatives. The rule is, if you need to use it, you must simplify it. 12.1 Maxima and Minima Relative Extrema: f has a relative maximum at c if there is some interval (r, s) (even a very small one) containing c for which f(c) ≥ f(x) for all x between r and s for which f(x) is defined. f has a relative minimum at c if there is some interval (r, s) (even a very small one) containing c for which f(c) ≤ f(x) for all x between r and s for which f(x) is defined. Absolute Extrema f has an absolute maximum at c if f(c) ≥ f(x) for every x in the domain of f. f has an absolute minimum at c if f(c) ≤ f(x) for every x in the domain of f. Extreme Value Theorem - If f is continuous on a closed interval [a,b], then it will have an absolute maximum and an absolute minimum value on that interval. Each absolute extremum must occur either at an endpoint or a critical point. Therefore, the absolute max is the largest value in a table of vales of f at the endpoints and critical points, and the absolute minimum is the smallest value. Locating Candidates for Relative Extrema If f is a real valued function, then its relative extrema occur among the following types of points, collectively called critical points: 1. Stationary Points: f has a stationary point at x if x is in the domain of f and f′(x) = 0. -
Secant Lines TEACHER NOTES
TEACHER NOTES Secant Lines About the Lesson In this activity, students will observe the slopes of the secant and tangent line as a point on the function approaches the point of tangency. As a result, students will: • Determine the average rate of change for an interval. • Determine the average rate of change on a closed interval. • Approximate the instantaneous rate of change using the slope of the secant line. Tech Tips: Vocabulary • This activity includes screen • secant line captures taken from the TI-84 • tangent line Plus CE. It is also appropriate for use with the rest of the TI-84 Teacher Preparation and Notes Plus family. Slight variations to • Students are introduced to many initial calculus concepts in this these directions may be activity. Students develop the concept that the slope of the required if using other calculator tangent line representing the instantaneous rate of change of a models. function at a given value of x and that the instantaneous rate of • Watch for additional Tech Tips change of a function can be estimated by the slope of the secant throughout the activity for the line. This estimation gets better the closer point gets to point of specific technology you are tangency. using. (Note: This is only true if Y1(x) is differentiable at point P.) • Access free tutorials at http://education.ti.com/calculato Activity Materials rs/pd/US/Online- • Compatible TI Technologies: Learning/Tutorials • Any required calculator files can TI-84 Plus* be distributed to students via TI-84 Plus Silver Edition* handheld-to-handheld transfer. TI-84 Plus C Silver Edition TI-84 Plus CE Lesson Files: * with the latest operating system (2.55MP) featuring MathPrint TM functionality. -
Visual Differential Calculus
Proceedings of 2014 Zone 1 Conference of the American Society for Engineering Education (ASEE Zone 1) Visual Differential Calculus Andrew Grossfield, Ph.D., P.E., Life Member, ASEE, IEEE Abstract— This expository paper is intended to provide = (y2 – y1) / (x2 – x1) = = m = tan(α) Equation 1 engineering and technology students with a purely visual and intuitive approach to differential calculus. The plan is that where α is the angle of inclination of the line with the students who see intuitively the benefits of the strategies of horizontal. Since the direction of a straight line is constant at calculus will be encouraged to master the algebraic form changing techniques such as solving, factoring and completing every point, so too will be the angle of inclination, the slope, the square. Differential calculus will be treated as a continuation m, of the line and the difference quotient between any pair of of the study of branches11 of continuous and smooth curves points. In the case of a straight line vertical changes, Δy, are described by equations which was initiated in a pre-calculus or always the same multiple, m, of the corresponding horizontal advanced algebra course. Functions are defined as the single changes, Δx, whether or not the changes are small. valued expressions which describe the branches of the curves. However for curves which are not straight lines, the Derivatives are secondary functions derived from the just mentioned functions in order to obtain the slopes of the lines situation is not as simple. Select two pairs of points at random tangent to the curves. -
Calculus Terminology
AP Calculus BC Calculus Terminology Absolute Convergence Asymptote Continued Sum Absolute Maximum Average Rate of Change Continuous Function Absolute Minimum Average Value of a Function Continuously Differentiable Function Absolutely Convergent Axis of Rotation Converge Acceleration Boundary Value Problem Converge Absolutely Alternating Series Bounded Function Converge Conditionally Alternating Series Remainder Bounded Sequence Convergence Tests Alternating Series Test Bounds of Integration Convergent Sequence Analytic Methods Calculus Convergent Series Annulus Cartesian Form Critical Number Antiderivative of a Function Cavalieri’s Principle Critical Point Approximation by Differentials Center of Mass Formula Critical Value Arc Length of a Curve Centroid Curly d Area below a Curve Chain Rule Curve Area between Curves Comparison Test Curve Sketching Area of an Ellipse Concave Cusp Area of a Parabolic Segment Concave Down Cylindrical Shell Method Area under a Curve Concave Up Decreasing Function Area Using Parametric Equations Conditional Convergence Definite Integral Area Using Polar Coordinates Constant Term Definite Integral Rules Degenerate Divergent Series Function Operations Del Operator e Fundamental Theorem of Calculus Deleted Neighborhood Ellipsoid GLB Derivative End Behavior Global Maximum Derivative of a Power Series Essential Discontinuity Global Minimum Derivative Rules Explicit Differentiation Golden Spiral Difference Quotient Explicit Function Graphic Methods Differentiable Exponential Decay Greatest Lower Bound Differential -
CHAPTER 3: Derivatives
CHAPTER 3: Derivatives 3.1: Derivatives, Tangent Lines, and Rates of Change 3.2: Derivative Functions and Differentiability 3.3: Techniques of Differentiation 3.4: Derivatives of Trigonometric Functions 3.5: Differentials and Linearization of Functions 3.6: Chain Rule 3.7: Implicit Differentiation 3.8: Related Rates • Derivatives represent slopes of tangent lines and rates of change (such as velocity). • In this chapter, we will define derivatives and derivative functions using limits. • We will develop short cut techniques for finding derivatives. • Tangent lines correspond to local linear approximations of functions. • Implicit differentiation is a technique used in applied related rates problems. (Section 3.1: Derivatives, Tangent Lines, and Rates of Change) 3.1.1 SECTION 3.1: DERIVATIVES, TANGENT LINES, AND RATES OF CHANGE LEARNING OBJECTIVES • Relate difference quotients to slopes of secant lines and average rates of change. • Know, understand, and apply the Limit Definition of the Derivative at a Point. • Relate derivatives to slopes of tangent lines and instantaneous rates of change. • Relate opposite reciprocals of derivatives to slopes of normal lines. PART A: SECANT LINES • For now, assume that f is a polynomial function of x. (We will relax this assumption in Part B.) Assume that a is a constant. • Temporarily fix an arbitrary real value of x. (By “arbitrary,” we mean that any real value will do). Later, instead of thinking of x as a fixed (or single) value, we will think of it as a “moving” or “varying” variable that can take on different values. The secant line to the graph of f on the interval []a, x , where a < x , is the line that passes through the points a, fa and x, fx. -
OPTIMIZATION 1. Optimization and Derivatives
4: OPTIMIZATION STEVEN HEILMAN 1. Optimization and Derivatives Nothing takes place in the world whose meaning is not that of some maximum or minimum. Leonhard Euler At this stage, Euler's statement may seem to exaggerate, but perhaps the Exercises in Section 4 and the Problems in Section 5 may reinforce his views. These problems and exercises show that many physical phenomena can be explained by maximizing or minimizing some function. We therefore begin by discussing how to find the maxima and minima of a function. In Section 2, we will see that the first and second derivatives of a function play a crucial role in identifying maxima and minima, and also in drawing functions. Finally, in Section 3, we will briefly describe a way to find the zeros of a general function. This procedure is known as Newton's Method. As we already see in Algorithm 1.2(1) below, finding the zeros of a general function is crucial within optimization. We now begin our discussion of optimization. We first recall the Extreme Value Theorem from the last set of notes. In Algorithm 1.2, we will then describe a general procedure for optimizing a function. Theorem 1.1. (Extreme Value Theorem) Let a < b. Let f :[a; b] ! R be a continuous function. Then f achieves its minimum and maximum values. More specifically, there exist c; d 2 [a; b] such that: for all x 2 [a; b], f(c) ≤ f(x) ≤ f(d). Algorithm 1.2. A procedure for finding the extreme values of a differentiable function f :[a; b] ! R.