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1,  Elements of Reason. 1996
1A. Pattern Based Reason  1995
1B. Math Curriculum Notes 1996
2. Three Skills for Algebra  1995
3 .Why.Slopes.&
.More.Math.1995

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6.-Euclidean-Geometry/Complex No.s 
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8.  Number Theory. 2006-7
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12.Real  Analysis 1995
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/ Reference - 08- 2008
1. Arithmetic
2. Algebra 
3. More Algebra 
4. Geometry  
5. More Geometry
6. Calculus

6. Restarting Calculus

Calculus is the college or senior high school mathematics subject required for college or university studies in accounting, business, money matters, science, engineering and health. 

Calculus  employs at full strength most earlier elements of high school mathematics:-  functions, trig, algebra (including polynomials), mathematical induction, more logic,  geometry and exact arithmetic met briefly or fully in high school mathematics.  

Calculus is very, very demanding.  Half the students who take college calculus fail.    

Step (III) below is very long.  So it and step IV are switched.

Step (I)  Starter Lessons or Inserts for the first days of Calculus

Following these inserts, resume your normal methods for calculus instruction as is

From 1983-89, before I left college instruction for five years of work in applied mathematics, I tried to make calculus easier for engineering and non-engineering students at the junior college and university level.  Calculus itself requires the algebraic way of writing and reasoning met in high school at full strength and beyond that introduces further demands, very, very suddenly in a way that leads to algebraic shock.  That being said,  easy max-min analysis of functions based on the relatively easy, algebraic, sign analysis of derivatives appears in the middle of a calculus course, and not at the start. By giving students formulas for derivatives or slopes in factored form at the start of a calculus course (even for students who have met calculus upto the level of the chain-rule), we can develop algebraic reasoning skills more slowly by  providing a preview of differential calculus, geometric and algebraic.  That will ease a few fears and difficulties.  Site lessons on why slopes (Geometric  Preview) , Two logic puzzles (Implication Rules) and Three Skills for Algebra were all developed to ease or avoid fears and difficulties of students entering calculus in fall 1983 in an effort to support inductive principles for instruction. 

Calculus students may start with weak arithmetic,  weak algebra and weak or imprecise reading and writing skills.  Before any short or complete review of high school mathematics, or further development of calculus, try the following geometric and algebraic calculus previews  

Chapters in and Postscripts to the online volume Why Slopes & More Math

  1. This Geometric  Preview gives a first image of calculus - to explain why derivatives are calculated and how they are used, and to give a context for earlier studies of slopes and rates of change. 

Algebra Preview:||
2 Slopes Revisited (V)
2 Skier in Motion (V)
2 The Skier (V)
2. Position Dependent (V)
3 Slope Sign Analysis (V)

 

Algebraic Preview Continued.
4 Single Factor Analysis (V)
4 Two Factor (V)
4 More Factors (V)
4 With Divisors (V)
5 Max-Min Tests
6 Discontinuities (optional)

The previews here provides a context for slope or derivative calculations, while developing algebraic skills slowly.   The algebraic preview here in fact takes the easy elements of later chapters on application of derivatives and put them first. That re-arrangement delays or slow the full-strength use of algebraic ways of writing and reasoning in calculus, while preparing students for it. 

To tackle weak or imprecise reading and writing skills, digress from calculus and present the two logic puzzle from this site's online chapter 2 on Implication Rules. Logic mastery (seeing the difference between one and two way implication rules  B if A (one way) and B if and only if A (two-way)  is a must for precision in reading and writing for calculus and studies in general.

For a first assignment, give arithmetic review problems with hints of algebra like the following to capturer and correct common arithmetic errors and to further develop or reinforce student algebra skills.  

 Arithmetic & Algebra Review  Exercises  to catch and correct common mistakes made by students entering calculus. 


 Markers for my assignments would be told to catch and correct all errors in notation and comprehension, so that my students have the chance to learn from their mistakes. 

That assignment could also include slope and further sign analysis problems following the algebraic, calculus preview models. 


(II). Insert to develop the algebraic viewpoint of limits  
or their dependence on parameters variables


The section Limits via Algebra in chapter 15 of the online volume Why Slopes & More Math include examples to help student make the transition from compute limits of the Newtonian quotient

lim        f(x+h) - f(x)
h-->0           h

for given values of x (say 2, 3, 5 and 7) to any value of x. That shows how the slope or derivative of a function y = f(x) may regarded as a function of x.

 

(IV) Employ as an Integral Calculus Preview 
        or starter lesson.
        

17 What is Area

18 Integration

18 Area Calculation
Chapter 17 and 18 offer a context for the discussion of areas under curves plus statements of the fundamental theorem of calculus.  All this is done without reference to summation notation for  Riemann Sums 

This summation notation free approach provides tutors and teachers a simpler route for defining the definite integral as limit of Riemann sums approximations to what area should be.

 

(III). Insert to develop or avoid epsilons and delta view of limits, etc

The decimal perspective of limits, continuity and convergence

More sections from online volume Why Slopes & More Math

The epsilon-delta viewpoint of limits, continuity and convergence requires a  high level of algebraic reasoning skills, too high for all students, even those who will entering the study of pure mathematics.  The epsilon-delta viewpoint may be dropped without injury to students knowledge of mathematics or preceded by a decimal viewpoint that requires the assumption of decimal representation for real numbers.  That assumption is needed in  present-day mathematics course designs or curricula which inherit the decimal-free axiomitc viewpoint of real numbers present for the sake of purity, if not practicality, in modern mathematics curricula of the mid-1950s and onward.  The latter curricula failed the general population in mathematics by emphasizing an axiomatic structure for real numbers and the development of algebra and calculus disjoint from common practices - use of decimals especially - and without any sanction for those practices.  As a student following the modern mathematics curricula too literally, I sensed that separation and was disappointed by a lack of sanction for mathematical practices which appear in daily life as well as in the numerical examples met in calculus. The remedy I think is to provide an applied mathematics curricula in which axioms for decimal representation of real numbers and coordinates in 1, 2 and 3D are explicitly assumed to sanction common practices.  That sanction would go beyond the reach of pure mathematics, but it would provide an axiomatic codification of applied mathematics practices  from arithmetic to the end calculus.  In that, axioms could be classified as pure or as applied, so that axiomatic structure of modern mathematics is preserved. To learn more, see the text Calculus by Lipman Bers (Holt, Rinehart and Winston 1969, SBN 03-065240-5).

Pure mathematics introduces a decimal-free or independent theory of  real numbers into studies for undergraduate mathematics degrees and into axioms for real numbers met in high school and calculus. But first courses on calculus today may use decimals to introduce and illustrate the concept of what is a finite limit in examples while employing a decimal-free definition of limits and continuity, and may call latter a more precise viewpoint. But in the practical study of numerical methods and error control in calculations, decimal appear and provide a more concrete, applied mathematics, approach to the definition and discussion of limits, continuity and convergence.  Chapter 14 in site volume  show or suggest how to make the definition, evaluation and properties of limits, continuity and convergence easier to learn and teach with greater simplicity and precision, modulo assumptions about the representation of real numbers by decimal expansion and about the convergence of the latter.  The decimal viewpoint can stand alone, be sufficient for most students. It can also be presented before the epsilon-delta view to make the latter more accessible in enriched calculus courses for gifted students, or in real analysis courses for undergraduate students specializing in a quantitative discipline or mathematics. 

Volume 3, Why Slopes & More Math

Chapter 14 - Sections to Read.

Chapter 14 - Excerpts.



14 Limits & Error Control and Continuityl

Details in Right Column

14 Limit of a Function

  • [Play Video]  4½ minutes: Algebraic View of Limits. Example involving sums and quotients.
  • [Play Video]  5½ minutes: Limits and Error Control for Linear Expressions
  • [Play Video]  2¾ minutes: Error Control to N decimal Places, say 5 or 10. 
  • [Play Video]  3¼ minutes:  Limits as Error Control for an unlimited number of decimal places.

14. Jumps and Limited Error Control  

Details in Right Column

14 Signif. Digit Error Control 

14 Cauchy Limits - Decimal explanation of why 
Cauch Sequence converge.

14  Limits of Sequence- Decimal Viewpoint.

14 Decimal Arithmetic.  Sum, differences,
 products and quotients of real numbers represented by infinite decimal 
expansions may be regarded as limits of the  corresponding operations on truncated decimal expansions. There-in a calculus level base to complete the thought-based development of decimal arithmetic in a manner sufficient and accessible to students not becoming mathematicians.

Limits, Error Control and Continuity

  • [Play Video]  4½ minutes: Algebraic View of Limits. Example involving sums and quotients.
  • [Play Video]  2½   minutes: Algebraic Properties of Limits I.
  • [Play Video] 2¼ minutes: Algebraic Properties of Limits II.
  • [Play Video]  5½ minutes: Limits and Error Control for Linear Expressions
  • [Play Video]  2¾ minutes: Error Control to N decimal Places, say 5 or 10. 
  • [Play Video]  3¼ minutes:  Limits as Error Control for an unlimited number of decimal places. 

Error control for the evaluation of functions y = f(x) provides a simple context and motivation for continuity and convergence.

Continuity at Point

To explain the idea of continuity of a function y = f(x) at a point x = a, we ask the following error-control question with b = f(a): to what number m of places should the decimal expansions of x and a agree, for the decimal expansion of the number f(x) to agree with that of b = f(a) to n-decimal places? That is, given a whole number n, is there an m such that
|x-a| < d = 1
2
· 1
10m
    implies    |f(x)-f(a)| < e = 1
2
· 1
10n
    (?)
An affirmative answer requires that agreement of x with a to m decimal places implies the agreement of f(x) with f(a) to n decimal places. An affirmative answer says unlimited accuracy and error control is possible at x = a.

The Greek letters d (delta) and e (epsilon) above are employed here in accordance with tradition of some (not all) calculus texts. For simplicity, the error control tolerances e and d in the first instance here and below, may be restricted to be numbers of the form [1/2] ·10-k = [1/2] [1/(10k)]. The decimal free discussion of error control and continuity dispenses with this requirement.

We say a function f(x) is continuous at a point x = a if and only if unlimited error control is possible there. More formally, we state the following definition.

Theorem 14.1 [Continuity at a Point] If f(x) is a real-valued function of a real number x in an interval [c,d], and a is a number in the interval [c,d] then the function f is said to be continuous at the number x = a if and only if the following holds. If for every n, there exist an m such that
|x-a| < d = 1
2
· 1
10m
    implies    |f(x)-f(a)| < e = 1
2
· 1
10n
·

Decimal-Free Form

The decimal-free description or definition of continuity at a point x = a is as follows.

[Continuity at Point] If f(x) is a real-valued function of a real number x in an interval [c,d], and a is a point in the interval [c,d] then the function f is said to be continuous at x = a if and only if the following holds: For every e1 > 0, there exist a d1 > 0 such that
|x-a| < d1     implies    |f(x)-f(a)| < e1
It is easily shown that the decimal-free and decimal-based definitions are equivalent. The proof of equivalence, better left to a second reading of this work, follows.

Proof of Equivalence.

To show the decimal-based description implies the decimal-free description of continuity, observe the following. First given e1 > 0, there is an n > 0 such that e1 > [1/2]·[1/(10n)] = e. The decimal-based requirement for continuity now is satisfied for some d = [1/2] ·[1/(10m)]. So the decimal-free version holds with d1 = d = [1/2]·[1/(10m)].

Conversely, the other way that is, to show the latter decimal-free form implies the decimal-based description of continuity, observe the following. Given m > 0, let e1 = e = [1/2] ·[1/(10m)]. Then choose d1 > 0 so that the decimal-free requirement is satisfied. The decimal-based version is then satisfied if m > 0 is selected so that d1 ³ d = [1/2] ·[1/(10m)].

Jumps and Limited Error Control

In some cases unlimited error control is not possible at the point x = a. It fails in the following case:

There is an e > 0 such that for every d > 0, there is some x satisfying the condition 

  |x-a| < d and |f(x)-f(a)| > e.

This means as the input x to the function y = f(x) becomes a better approximation to the number a, there is no guarantee the difference |f(x)-f(a)| will be smaller than the error control target e. This concept is illustrated by functions whose graphs have a few jumps in them. The height of the largest jump near a point x = a indicates how small the target tolerance e or [1/2]·10-n can be in the discussion of error control.

Again, unlimited error control is possible in the following circumstances:


For each target tolerance e > 0, there is a tolerance d > 0 such that the condition 

  |x-a| < d and |f(x)-f(a)| £  e.

These circumstances appear when f(x) is continuous at x = a.

Computations on machines with finite accuracy precision arithmetic, restrict the number n of decimals places that can be accurately computed. Every computing machine which calculates to finitely many binary or decimal places, suffers from such a limit. Small discontinuities in calculations appear, except in those case where exact arithmetic can be done. For example, on a computing machine which computes to at most n0 decimal places, the existence of a rule of the form
|x-a| < 1
2
1
10m
    implies    |f(x)-f(a)| < 1
2
1
10n
governing error cannot be guaranteed for n ³ n0 and can be considered improbable for most functions evaluated numerical by a computer. An exception is provided by functions whose numerically values can be represented (or encoded) exactly on a machine.

On a computing machine which computes to at most n0 decimal places, the error control of a single addition and multiplication are guaranteed to only n0 binary (or decimal) places. Digits beyond the n0 place are uncertain. If several such calculations are done, with numbers in one calculation being used in the next, errors accumulate and accuracy is lost. The calculations in question may have to be reorganized to improve accuracy.

 


Calculus students & teachers need to know about methods to ease algebra shock in calculus by starting with calculus previews, by reviewing 3 skill for algebra, and by basing calculus concepts on the decimal concepts alone or before decimal-free ones. First weeks of calculus often rush through key elements of high school algebra - functions especially. 

To learn more, see site pages on calculus and, if you insist, on real analysis

 

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