Appetizers and Lessons for Mathematics and Reason 
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||Définition d'une variable || Algèbre || Arithmetique || Logique ||La raison basée sur les règles et modelés||

Online Volumes (Book Orders)
1,  Elements of Reason.
1A. Pattern Based Reason 
1B. Math Curriculum Notes
2. Three Skills for Algebra
   Three Skills for Algebra
3. Why Slopes & More Math
 Avid Readers: Try Pattern Based Reason  & chs 
 1 to 12, 14,  16 & 17  in  Three Skills for Algebra.
More Site Areas 
1. Help Your Child/ Teen Learn 
2. Solving Linear Equations  
3. Fractions Ratios Rates Proportions, Units
4. Euclidean Geometry
5. Analytic Geometry/Functions 
6. Number Theory
7. Calculus Introduction
8. Complex Numbers 
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9. Quebec Maths Education  
10. Secondary IV(?) maths
11. Real  Analysis 
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14. Algebra, Odds & Ends, Etc
16  LAMP - Course re Design Plans
17. Math Education Essays
Teacher-Tutor Info & How-TOs
1. Arithmetic Reference
2. Algebra Starters 
3. More Algebra 
4. Geometry Starters
5. More Geometry
6. Calculus Modifiers 
7. Multiple Logics in Maths
8. Math Ed. Issues

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YOU are better than YOU think. Show yourself  how:  

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Read  logic chapters 1 to 5  in online volume Three Skills for Algebra  for greater skills & confidence in  work 
and study.

Learn to read notes and textbooks like a lawyer, so that no nuance, no subtlety and no clause escapes your attention.

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 Logic chapters 1 to 5  re- appear not in sequence, as is or longer,  in  Volume 1A,  Pattern Based Reason, Bon Appetite.

Logic Mastery
 Amazing, Amusing, Amorous,  Delicious, Delightful, Edifying, Strengthening Elixir. 
It eases work & learning difficulties Makes the hard easier. Opens eyes. Leads to greater precision.
in reading and
writing

Logic mastery makes the hard, easier. Logic mastery  leads to better, stronger and richer comprehension.  Logic mastery  improves reading and writing.  Logic mastery ease learning difficulties.  Logic mastery gives a headstart.  In sum, logic mastery  will develops critical thinking, improve reading and writing, and give a firmer base for work and studies at many levels. Good luck.


After logic  (a) continue reading Three Skills for Algebra, chapters 8 to 14  and do so alongside site area on solving liinear Equations ; or (b) see this calculus starter lesson and Volume 3, Why Slopes  & More Math, chapters 2 to 6;

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Caution: Site advice is approximately correct, for some circumstances, not all. That leaves room for thought

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What may be learnt and when depends on how skills and concepts are developed. Making the hard easier and clearer will allow earlier & richer development of skills and concepts.


Try the Twiddla Whiteboard. In principle, it  allows to people to draw and chat together online on a copy of this webpage or a clean sheet. The chat may be via text or audio.  Visit www.twiddla.com to set up whiteboards to work with the webpage of your choice.

For online automated help in senior high school maths & calculus, visit  quickmath.com  For Automatic Calculus and Algebra Help with derivatives, integrals, graphs, linear equations, matrix algebra, visit calc101.com  With  overlap, each site quickmath & calc101offers a different range of services, some free, some not, all based on webmathematica. Good luck.

Chapter 17
Area Approximation

Saying precisely how to compute a quantity defines it.

Covering A Region by Squares

The areas of squares and rectangles may be calculated by calculating the product of the lengths of their sides. In the plane, the area of a bounded region S rectangular or not, may be approximated by covering the region S concerned with small squares, all of the same size, overlapping, if at all, only at their edges.

The example of an elliptic shaped region S is shown. Each covering by small squares gives three methods for approximating what the area A of the region should be.


     

  1. An inner (or lower) approximation to the area A of the region S can be obtained by summing up the areas of all the squares contained completely in the region S. This inner approximation is expected to yield an estimate lower or £ A.
  2. An outer (upper or over) approximation of the area can be obtained by summing up the areas of the squares which have an interior point in common with the region. This outer approximation is expected to yield an estimate higher or ³ A. (A point in a square but not on an edge is said to be an interior point of the square.)
  3. A middle approximation might be obtained by adding to the inner approximation, the areas of those square which are completely in or more than half-in the region S. Other in-between approximations are possible. Intermediate approximations yield an middle area estimate between the upper and lower estimates.

    FOOTNOTE: From a computational perspective, more than half-in but not completely in is not easy to define. This could be a matter of visual judgment - a step outside of the domain of rule-based mathematics. To give a mathematical algorithm, the toss of a coin might be sufficient, or a judgment could be made on how many of the four triangles formed by the diagonals are included completely in the region S.

One or more of the above approximations may be familiar to you from your elementary school days.

Each of the above approximations is expected to improve as the squares are quartered (their sides halved) repeatedly and indefinitely. The latter would cause the lower estimate to increase, the upper estimate to decrease while the middle estimate together with the area A presumably approximate, remaining in between. Such halving results three sequences of numbers or quantities.

Note: The lower estimates yield the increasing sequence, the upper estimate yield the decreasing sequence, and the middle estimates yield a sequence between the previous two.

The area A should be the common, finite, limiting value L of the approximations as the sides of the covering squares become smaller (approach zero). This says how to compute the area A with an unlimited accuracy if a common, finite limiting value L exists for the approximations.

The area of a region is defined by the methods for approximating it. That is, the region has an area A = L if and only if the three numerical approximations described above all approach a single finite limiting value L. This limiting L is then called the area of the region. Otherwise, with some disappointment perhaps, we may say that the area is not defined. (Alternatively, we might define inner and outer areas using the limiting values of the inner and outer approximations and identify circumstances in which they are equal.

FOOTNOTE: For instance, for some odd (pathological) region, inner and outer area approximations may approach an inner limit Linner and an outer limit Louter which are not equal. Regardless, these limiting values may define what is meant by inner or outer concepts of area. There has been a concern with identifying conditions in which inner and outer approximations etc approach the same limits. For more information, a very specialized (that is, not for everyone) book or course on area computation, more precisely, integration theory, is indicated.

 

www.whyslopes.com
Volume 3,  Why Slopes and More Math
-  

Foreword, One Calculus  preview and Online Chapters: (V) signals video (RealPlayer Format)  to watch 

Area Entrance & Hub
Foreword
Chapter Descriptions
1. Introduction
2. Calculus Starter Lesson
2. Second Preview Begins
2 Skier in Motion (V)
2 The Skier (V)
2. Position Dependent (V)
3 Slope & Extrema (V)
4 Single Factor Analysis (V)
4 Two Factor (V)
4 More Factors (V)
4 With Divisors (V)
5 Maxima & Minima Tests
6 Jumps & Discontinuities
8 Review  (optional)
9 On Calculus Studies
11 Slope of Slope
13  Acceleration
14 Limits & Error Control (V)
14 Limit of a Fn.
14. Limited Error Control
14 Signif. Digits
14 Cauchy Limits
14 Sequence Limits
14 Decimal Arith.
15 What is Slope (V)
15 Slope Calculation (V)
15 Slope, a Limit
15 Tangent Lines
15 Linear Approx.,
15 Limits via Algebra (V)
15 Recap.
PS.Chain Rule for Polys
PS Chain Rule- General  (V) -
PS More Chain Rule (V)
PS - Sign Analysis (V)
16 What is Velocity
17  What is Area
18 Integration
18 Area Calculation
18  Fn DefN, 6 Ways
19 Logs & Powers
19 Natural Log.
19 Exponential Fn.
20 What's Next
21 Add Vectors
22 Complex #'s
23 Complex #'s
23 Trig Identity
23 Proofs of.
24 Complex Logs etc

Units in Calculations:
7 Velocity
7 Varying Velocity Example
7. Velocity Calculation
7 Changing Units
7 Same Velocity  Motions
10 Slopes without Units.
10 Units & Slopes
10  Units in Cost vs. Quantity
10  How Units  Appear
10 Unit  Elimination
10 Partial Elimination
10 Interest & Units
12 More on Units
Content Guide

Enriched material: The Appendices of Volume 3 are located in the Real  Analysis  Area.

Pigeon Hole Principle
Constant Difference Thm
Continuous Functions
Rational Functions
Mean Value Theorem
One Side Range Theorem
Range On One Side Theorem
Integration & Lipschitz
 Continuity


These appendices continue the
decimal viewpoint of limits, error
control and continuity begun
in Chapter 14. The One Sided
 Range Theorem
is a postscript,
not in printed version.



Online Volume 2, Three Skills for Algebra, Chapters 1 to 25 - skip 18., verbalizes and explains key skills and concepts, those needed in calculus, again to make the hard easier. A visual understanding of complex numbers may help - serve as back ground info,  in partial fraction decomposition.

 

 


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