Appetizers and Lessons for Mathematics and Reason (www.whyslopes.com)
||Définition d'une variable || Algèbre || Arithmetique || Logique ||La raison basée sur les règles et modelés||

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

 (Optional Book Orders)
More Site Areas 
1. Help Your Child or Teen Learn 
2. Solving Linear Equations
3. Fractions Ratios Rates Proportions & Units
4. Euclidean Geometry
5. Analytic Geometry/Functions 
6. Number Theory
7. More Calculus
More Site Areas 
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9. Qc Maths  Education  
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15. Algebra, Odds & Ends, Etc
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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

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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 18
Rules for Algebra

Previous:To Divide, Multiply by reciprocal 1-X

Rules for Division or Fractions

where denominators and numerators are whole numbers, integers or real numbers, complex numbers or polynomials etc.

By replacing subtractions and divisions in formulas with additions and multiplications, we get formulas only involving additions and multiplication. These new formulas give the same result as the original ones. They can be changed, say rephrased, using the properties of real numbers and quantities given above. After this, for cosmetic reasons depending on circumstances, some multiplications and additions might be replaced by divisions and subtractions.

The rules for doing arithmetic with fractions and divisions can be obtained from the properties of real numbers if we use the equality
a
b
= a . 1
b

 to define the "fraction" a/b whenever (a,b) is a pair of real numbers with the second number b non-zero.

So instead of properties of addition and multiplication, you can use the following rules which say when two different fractional expressions give the same results.  These rules provide methods for arithmetic operations on fractions where the numerators and denominators are real (or complex) numbers or polynomial expressions whose values are real (respectively, complex) numbers.

First, the cancellation rule says
a c
b c
= a
b
whenever a, b and c are both nonzero real numbers or quantities. Here there is no condition on a other than it be a real number or quantity as well. (Remember division by zero is not permitted as division by zero is not defined.)

Next, one fraction addition method gives

a
b
+ c
d
= ad+cb
bd
whenever b and d denote nonzero real numbers.

But if we use a common denominator M, we can rewrite the foregoing as
a
b
+ c
d
= a(M¸c)+c(M¸d)
M

In the case where numerators and denominators are given by integers or polynomial expression, simplification of the expression of the right requires less work if M is taken to be the least common multiple of the denominators b and d.

Finally, we state the nameless rule

a· b
c
= ab
c

for multiplying a fraction by a real number a, or a real-valued expression a.


Chapter Sections: Up ] 18 Changing Formulas ] 18. Proper Use of Equal Sign ] 18. Replacement & Substitution ] 18 Real Numbers & Quantities ] 18 Rules for Algebra ] 18 Sums as Factors I ] 18 Sums as Factors II ] 18 Addition Properties ] 18 Sum Associative Property ] 18 Sums and Number 0 ] 18 Replacing Subtraction by Addition ] 18 Times Properties ] 18 Sum Grouping and Ordering ] 18 Product Associative Property ] 18 Products with the Number 1 ] 18 Product Grouping and Ordering ] 18 Power Rules ] 18 To Divide, Multiply ] [ PS: Rules for Fractions and Division ] 18 Inconsistent Nttn ]


 

www.whyslopes.com
Volume 2, Three Skills for Algebra -

Preview, starter & further lessons for logic and algebra to (i) improve work & study skills;  (ii) to  to ease or avoid algebra (math) fears & difficulties; and (iii) to fill gaps in the exposition of mathematics.

Foreword, Chapters and Appendices follow.

Foreword
1. Introduction
2. Implication Rules
3. Chains of Reason
4. Romeo and Juliet
4. Induction Mathematical
5 Knowledge Islands
6  Old Language
7  Arith Skill Check
7. The Next Chapters
8 The Three Skills
8 VNR-Concise-Encyclopedia
PS. What is a Variable
9. Algebra Talk
10 Two More Skills
11 Why Shorthand
12 Shorthand Usage
13 What's Next
14 Compound Interest
15 Linear Equations
PS I.  Distributive Law
PS II. Polynomials
16 Painless Proofs
17 Pythagoras
18 Rules of Algebra
19  Functions & Sets
20 Degrees & Radians
21 What's Next
22. Arith & Geometric Sums
23 Summation Notation
24 Your Money
25 Induction & Recursion
26 What's Next
27 Pronouns in Logic
28 Occurrence Tables
29 Contrapositive
30 Truth Tables
31 Indirect Reason
A. Advice For Learning

Real Player Videos

Perfect arithmetic skills with whole numbers & fractions
after or besides chapters 1 to 14.

Arithmetic Videos Summary
Addition with Decimals
Subtraction with Decimals
Multiplication with Decimals
Fraction Arithmetic
Recognizing Primes
Long Division for Decimals
Square Root Simplification
Greatest Common Divisors
Least Common Multiples

Words Before Symbols: 
What is a Variable?
Introduction
Variation between Examples

Variation of Letters

A letter denotes a variable

Cases of Double Variation

Three Notions of a Variable

Constants, Parameters
& Variables

Talking about numbers
Dependent or Independent
Variable, a Matter of Choice
Complex number: starter lesson  

Solving Linear Equations:

A. Letters and Lengths

B. & C. Solving Linear Eq'ns
with stick diagrams.

(i) x + 20 = 29
(ii) 2x + 5 = 20
(iii) 3x + 10 = 32
(iv) 5a + 16 = 3a+ 24

(v)  (½)x + 8 = 24½
(vI)  (¾)a + 16 = (¼)a+ 24
(vii) (¾)q + 17 = 32
(viii) 13 =[2/3]x +7 twice
(x) Animated Examples
(i) Integral Coefficients (A)
(ii) Integral Coefficients (B)
(iii) Fractional Coefficients

(iv) With Parameters

Problem Solving with Linear
Equations in one or many
unknowns, and in essentially 
one unknown - Symbols before
words. 


C. Solving Linear Eq'ns 
without
Stick Diagrams

D. Problems in 
essentially one unknown

E: 2D Systems - Sub Methods.
F. Larger Systems




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a 1983 McGill. Ph. D. in mathematics
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