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 
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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  & 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

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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.

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.

Intersection of Lines

When a point [x,y] is on two lines, it must satisfy the equations of both.  This observation leads to two "linear" equations in two unknowns

                         ax + by = e

                         cx + dy = f

These simultaneous equations must have a unique solution if the lines are different and not parallel.  The equations of lines y = e can be rewritten in the form ax+by = e with b = 1.

To find the intersection point of a line y = m1x + b1 and y = m2x + b2 , solve the equation m1x + b = m2x + b2 for x and then compute y.    The two simultaneous equations 

y = m1x + b1 and 
y = m2x + b

can also be solved in any way you wish.  Subtraction of one from the other would eliminate y immediately. 

Working with the set model of a line

 In the algebraic view, we may say or define a LINE is the set of solutions (x,y) to an equation  y = mx +b. Then the two-point formula for the coefficient m, here 

m = (y2  - y1)/(x2  - x1
    = rise/run 

is a consequence of the equation without any reference to lines drawn in the plane.

By describing a LINE as a set of points satisfying an equation, we obtain a numerical model for a geometric object, the physical line in the plane, with which we work algebraically and exactly apart from the approximation we do with fat points (dots) and thick lines in the plane. Drawing errors are thus removed.

Which is more reliable: Geometry with or without coordinates?

 The solution and properties of equations in analytic geometry  provides a model in which  reasoning with numbers and algebra exactly replaces the suggestive geometric reasoning in which a single diagram represents and approximates many.

 


 

 

 



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Analytic Geometry
& Functions, etc

Area Entrance 
Entrance + Pages Below this page



Pages at Current Level (L)  Numericall Intro
(L)  Deriving Eq'ns
(L)  Perpendicular Lines
(L)  3 Eqn Forms
(L)  Algebraic View
(L) Finding Intersection Points
(L) Coordinate Only Geometry.
(L) Exercises
(L) Lines Summary
(L) Lessons Elsewhere

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?

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The Rest © 1995 onward by site author,   Alan Selby,
a 1983 McGill. Ph. D. in mathematics
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