Appetizers and Lessons for Mathematics and Reason 
www.whyslopes.com - mathematics as an art and discipline, step-by-step  Parents: See Help Your Child/ Teen Learn 
Français
:
||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  & chaps   1 to  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 
More Site Areas 
9. Quebec Maths Education  
10. Secondary IV(?) maths
11. Real  Analysis 
12. LaTeX2HotEqn:
13. Electric Circuits Etc  
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

Back ] Area Entrance ] Up ]


YOU are better than YOU think. Show yourself  how: 

      |      
//  _   _ \\
/\             /\
  <|  (o)   (o)   |> 
 \     | |      / 

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

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

 -/[]\- 
||
   / \_ 
 ||||||||||||||||||||||||||||

 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;

      |      
//  _   _ \\
/\             /\
<|   (o)   (o)  |> 
     | |     |
   \             /   
\    =   /

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

 -/[]\- 
||
  _ / \     
 ||||||||||||||||||||||||||||

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.

Column Multiplication Method

The association of products of whole numbers with counting sub-rectangular divisions of a larger rectangle leads to visual aids for developing and applying the generalized distributive law for whole numbers, fractions, proper or not, and nonnegative real numbers in general. 

The following animated example gives another area based example of how to example a product of two factors, when each factor is a sum of positive terms or lengths.

Problem: How do we express a product 

NM = (a+b+c)(e+f+g) 

as a expression of the terms a to g?

Solution:  The number NM gives the area A of the blue rectangle - first calculation thereof.

 b    c 

 e 

     
 f        
     

The BLUE rectangle can be divided into  subrectangles

 b    c 

 e 

 ea  eb ec
 f   fa fb fc
 ga gb gc

Next sum all sub rectangle areas, row by row.

 b    c  Row  Sums

 e 

 ea  eb ec ea + eb + ec
 f   fa fb fc fa + fb + fc
 ga gb gc ga + gb + gc

So then the area A = ea + eb + ec+ fa+ fb +fc +ga + gb + gc as well. That gives the second calculation of area.  Therefore

(a+b+c)(e+f) = ea + eb + ec+ fa+ fb +fc +ga + gb + gc

as we assume different way of a calculating an area give the same value.

Remark 1: The foregoing visual or geometric derivation the generalized distributive law  holds for non-negative rational and irrational numbers a to f with unit length in place of the word rows and columns if we derive and then use the additive properties of area - the area of a rectangle equals the sum of areas of a set of subrectangles covering it - subrectangles which intersect only at their edges. Details will be given later. 

Column Methods for Multiplication

 We may replace the rectangles above by multiplication tables in which the terms in the factors provide the initial entries in rows and columns. 

 b    c  Row  Sums

 e 

 ea  eb ec ea + eb + ec
 f   fa fb fc fa + fb + fc
 ga gb gc ga + gb + gc

Further table entries are obtained via products. The foregoing can be tabulated as a column method for multiplication:

 a + b + c
 e + f                           x 
ea + eb + ec                 = product of first row with e
fa + fb + fc                 = product of first row with e
fa + fb + fc                   +   = product of first row with f
ea + eb + ec+ fa+ fb +fc  =   (e+f)(a+b+c) or (a+b+c)(e+f)
                                    as multiplication is commutative

 

Remark: Even though the justifications above are only for positive real numbers, the calculations holds for real numbers.

While the principle of permanence of algebraic form or patterns was not a valid logical principle in the development or proof of  properties of growing sets of numbers from natural numbers to real and complex numbers,  in education the accidentally permanence of algebraic form can be a pedagogical tool in the development of algebraic skills and concepts.  Assuming that counting by grouping and the measure of perimeters, areas and volumes is independent of how counted or calculated. That provides a quick logical base for algebraic reasoning in the case of positive quantities, those identifiable with counts or measures. All the foregoing may lead to a logical development of algebra in which justifications are given for calculations involving positive quantities while students are informed that justification for general case involving positive, zero and negative quantities is a subject for further advanced study.

Students or teachers insist on the justification for general case, that is real numbers instead of only positive numbers, can develop proofs that apply mathematical induction and the distributive law, pattern or axiom for real numbers. Go to the site Number theory areas to learn more when you have time to spare

 


www.whyslopes.com
Analytic Geometry
& Functions, etc

Area Entrance 
Entrance + Pages Below this page



Pages at Current Level (P) Area View of Products
(P)  Multiply, Add, Subtract
(P) Long Division I
(P) Long Division II
(P) More Column Methods

Area Entrance
(C) Complex Numbers
(FN) What are Functions?
(FN) Functions - More
SZM: Sign Analysis
(L) Lines Summary
(P) Polynomials (*,+,-)
(Q) Quadratics
(D) Simplify Square Roots
(T) Unit Circle Trig
Conic Sections
Links
More Links
Pages at Above this Page

Extras:  Not all perfect.

Equal Sign Use/Abuse
Real Numbers
Say More Positive
Linear Inequalities
Triangle Inequality
Absolute Value |x|
|x| Eq'ns & Inequalities
Rectangular Coords
Shortest Path
Distance Formulas
Add & Multiply Points
Polar Coordinates
Radians
(A) Vectors
(A) Coordinate Arithmetic
(A) Navigation on Maps
(A) Addition Geometrically
(A) Rotation
(PT) Translations
(PT) Dilatations
PT: Rotations


Links to Site Pages outside this site area follow - co- and pre- requisites.

Road Safety Message

Easy Consequences of  this (newest) Complex Number. Starter Lesson follow below to provide an alternate development of HS or college maths.

Vec & Cmplx  No Applet
B2 C. Conjugates
B3 Pythagoras
B4 Distance
B5 Rt Triangle Similarity
B6 Trig., Functions
B7 Dot & Cross Products
B8 Cosine Law
B9 Exponential & cis fns
B10 Easy Trig Identities
B11 Set Viewpoint

Arithmetic Videos - Real Player Format

Decimal Addition Methods
Decimal Subtraction Methods
Decimal Multiplication Methods
Decimal Division Methods


Fractions
Primes
Greatest Common Divisor
Divisors

Least Common Multiples

Square Root
Simplification

Using formulas forwards & Backwards - A unifying theme for algebra skill development - the 4th skill in Volume 2, Three Skills for Algebra!

What is a Variable?

www.whyslopes.com
[Top of this Page] [Site Exit] Back ] Area Entrance ] Up ]
[Comments, Reactions, Feedback][ Road Safety Message ]
: Favourite SitesBBC News  and mathematics portion of  English National Curriculum  

ll trademarks and copyrights on this page are owned by their respective owners.
Copyright to comments & contributions are owned by the Poster. 
The Rest © 1995 onward by site author,   Alan Selby,
a 1983 McGill. Ph. D. in mathematics
All Rights Reserved.