|
| |
Algebra Hints
Decimals and decimal expansions may represent real numbers exactly or
approximately. Symbolic arithmetic avoids the approximations. It employs
signs and natural numbers, alone or in fractions - for example 18, ¼ , ½ and ¾. It
employs symbols such
as π (pi) and e (the natural number) to denote the "exact" values
of key real numbers. In the case of square roots
_
Ö h
and further roots, decimal approximations are avoided, and cosmetic
conventions are followed to simplify them. Those conventions are
presented below.
The simplification is shown with or without the use of primes. Here
computation may equal not the decimal approximation but the algebraic or
cosmetic simplification of square roots. The examples below show how
factorization and prime decomposition, together or not, may be used in the
simplification process and also providing a stopping rule.
Real Player Videos give more examples. View
them before, after besides the text below.
Square Roots of Whole Numbers without a calculator
If you have a calculator, you may compute or represent the square root of a
number exactly or approximately. But in algebraic calculations (or shorthand
mathematical reasoning with letters and symbols), approximations are to be
avoided. The latter may be done using the following methods. Some of these
methods are cosmetic. But their use leads to a common or standard form for
expressions involving square roots.
Irreducible Case - Leave as is
If h is prime or a product of primes to the first power then no
simplification of the square root
__
Ö h
is possible. Leave as is.
Reducible Case if h is a perfect square
If h = n2 and n > 0 then
Examples
__
Ö 9 |
= 3 |
|
___
Ö 25 |
= 5 |
|
____
Ö 169 |
= 13 |
|
Combined Case
h = a2b is a product of a perfect square a and another number b
which may or not be irreducible.
For a > 0 and b > 0,
__
Ö h |
= |
___
Ö a2b |
= |
a |
__
Öb |
Examples
____
Ö 500 |
= |
______
Ö (100)5 |
= 10 |
__
Ö 5 |
____
Ö 27 |
= |
______
Ö 323 |
= 3 |
__
Ö 3 |
_____
Ö 1200 |
= |
_______
Ö (100)12 |
= 10 |
___
Ö 12 |
___
But Ö 12 |
= |
____
Ö 223 |
= 2 |
__
Ö 3
|
Therefore
_____
Ö 1200 |
= 10 |
__
Ö12 |
= 10(2 |
__
Ö 3 ) |
= 20 |
__
Ö 3 |
Simplification Revisited
If h = a2b where the prime factorization of b only includes
primes, but no powers of primes (other than 1). Then
Example
h= 1500 = 500*3 = 3*22*53 = = 3*22*52*5=
(22*52) 3*5 = (2*5)23*5
gives
____
Ö1500 |
= |
2*5 |
___
Ö3*5 |
= |
10 |
__
Ö15 |
|
More Simplifications:
For a > 0, b > 0 and c > 0,
_____
Ö a2b2c |
= |
ab |
__
Ö c |
Example
_____
Ö 1200 |
= 10 |
_______
Ö100*4*3 |
= (10*2) |
__
Ö 3 ) |
= 20 |
__
Ö 3 |
Suppose h = a2b where the prime factorization of b only includes
primes, but no powers of primes (other than 1).
- [Play
Video] 5 minutes - Calculation of Squares and Square Roots
for Natural Numbers without and with decimal approximations. Exact
representation of square roots without approximation requires not
using a calculating. That is important in algebra - the statement
and derivation of formulas.
- [Play
Video] 1¾ minutes - How to Compute Square Roots by
Factorization
- [Play
Video] 3 minutes - Computational Properties - More on square
computation by factorization.
- [Play
Video] 3 minutes - Examples of square root computation by
factorization.
- [Play
Video]3¾ minutes - Examples of square root computation
by prime factorization.
In algebra, this simplification rewrites square roots in a standard
form, a standard that may lead to a common representation of square
roots of whole numbers when they appear in formulas and the derivation
or justification of formulas.
|
Online Volumes
1Elements of Reason
1A. Pattern Based Reason
1B. Mathematics
Curriculum Notes
2. Three Skills for
Algebra
3. Why
Slopes and
More Math
More Site Areas:
Helping
Your Child or Teen Learn.
Solving
Linear Equations with Stick Diagrams
Fractions,
Ratios, Rates, Proportions & Units
Euclidean
Geometry
Analytic
Geometry
Number
Theory.
Calculus
Intro
Complex
Numbers
Quebec
Maths Education
Real
Analysis
LaTeX2HotEqn
Great Expectations: If you can learn to follow a
multi-step methods in any subject precisely, you can do so in other subjects, as
well.
Good news: Site pages identify
what you need to study.
Bad news: Site pages do not explain
everything
More Bad News: Learning takes time,
yours.
| |
|
www.whyslopes.com
Analytic Geometry
& Functions
[#] shows no. of lessons.
Up Equal Sign Use/Abuse Real Numbers Simplify Square Roots Absolute Value |x| Say More Than Theory of Inequalities |x| Eq'ns & Inequalities Rectangular Coords 1, 2&3D Distance Formulas - 1, 2 & 3D Shortest Path Triangle Inequality Point Addition & Real Multiples Polar Coordinates Radians (A) Vectors (A) Coordinate Arithmetic (A) Navigation on Maps (A) Addition Geometrically (PT) Translations (PT) Dilatations (A) Rotation (C) Complex No. Intro (C) Distributive Law - Applied (C) Properties (C) Complex Conjugates (C) Pythagoras Thm, New Proof (T)Trig on Unit Circle (T) Complex No.s &Trig (T) cis or exponential FNS (T) Dot & Cross Products (T) Cosine Law (T) Pythagoras Converse
Section Entrance
Links More Links learn more Two Treatments of Geometry BIG Table of Contents conic sections briefly
|
|
|
For Parents & Teachers: Speaking
Skills, Reading
& Writing,
Preparing for Science, ends,
values and methods for work and study, parent- friendly mathematics booklets for ages 4-14.
-
Math
Education
Essays (opinions,
possibilities, references)
- POMME, a two
level program for future skill development in
schools and colleges worldwide. Address content &
motivation gaps with ends, values & methods for skill
development to say which way to go, how and why. -
Present Day Curriculum:
(A) Secondary
I Mathematics
consolidate fractions and measurement, skills and
sense consolidation,
(B)
Secondary II Mathematics
year of algebra and proportionality
(C) See too the following:
- Arithmetic
& Number Theory Practices (horribly put, but
useful)
- Algebra and
Logic SubProgram
(well put, extremely useful)
For Avid Readers in School & Out -
Online Books
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
Tour their forewords.
Calculus Prep or Help: See Volumes 2 & 3,
and this bigger
Calculus
Guide.
|
|
|
|
Senior
High School &
Calculus Students
|
|
|
|
Free Live Lesson
- Operations with Decimals - Comparison, Subtraction and Long Division
- Click here
to attend.
|
|
|
|
For Senior
High School Mathematics & Calculus
Intro to Solving
Linear Equations
- a different paths for junior and even senior high
school students.
5
wordy Logic
Chapters
4 curious Algebra
Chapters
Words before & besides symbols. A Key Algebra
forward & backwards Chapter
First Calculus
Preview (1st intro)
Four Calculus
Chapters
(2nd intro)
Intro to Complex
Numbers (long)
Intro to Mathematical
Induction (romantic & wordy at first)
|
|
|
|
Many More Topics
1. Decimal
Arithmetic Reference!
2. Integers
- Intro to Signed No.s
3. Fractions
- fully explained.
4. Fractions
with Units
5. Number
Theory,
6. Solving
Linear Equations
7 Formulas
Use Forward & backwards -
8. Proportionality,
Back- & For-wards.
9. Logic
Chapters:
10. Euclidean-Geometry
11. Slopes
& Equations of Straight Lines. (Take
I. See take II below)
12. Why
Study Slopes.
13. Maps,
Plans, Similarity & Trig,
(Take II included here)
14. Quadratics:
Starter lessons
15. Polynomials:
Starter lessons
16 Why
Factor Polynomials:
17 Functions
- Forwards & Backwards.
18. Exponents,
Radicals & logs.
19. Complex
Numbers before trig (new advance/ starter lesson)
20. DC
Electric
Circuits Etc
21. Real
Analysis
22. The
Olde Complex No, Trig
& Vector Section.
23. More
Calculus Stuff
- written after Volumes 2 and 3.
More For Instructors
-
Education
Essays
(opinions,
possibilities, references)
- POMME, a two
level program for instruction K1-14
- Math & Logic How-TOs
1. Arithmetic
2. Algebra
3. More Algebra
4. Beginner Geometry
5. More Geometry
6. Calculus
7. Show Work or Logic
These may be too dense for students.
Level I Material: New Stuff
Time and Date Matters
Level I Arithmetic.
Money Matters
Measurement Matters
Matters of Chance (Risk Control)
Logic
Chapters
(leave what's not clear in Level I to Level II)
Using/Making Maps and Plans.
(A variant of
Maps,
Plans, Similarity & Trig, to
appear here).
|
|
|
|
Skill Development Tips
For All
Standards: (A) Take
care to avoid the domino effect of errors & approximations; (B) Do and
record steps in an manner that allows skill mastery to be seen or
corrected. Anything represent substandard work.
Key Numerical Methods
- To multiply signed numbers, prefix the product of their signs to the product
of their lengths or unsigned parts. The product is negative if the no of
negative sign in it is odd.
- To add signed numbers with like signs, prefix the common sign to the sum of the
lengths.
- To add signed numbers with opposite signs, prefix the sign of the longest to
the difference: length of longest minus length of shortest.
- Should we study roots and powers of real numbers with formulas involving exponential and log.
- How does adding and multiplying points in the plane and rotating the midpoint
of a line segment lead to mastery of complex numbers and the thought-based
development of their properties, all before trig?
- New Axioms for High School Mathematics: In accounting, totals of assets
and debts may be calculated by dividing the assets and debts into
non-overlapping (disjoint) groups and then adding subtotals. In general, sums
(and products) of counts and numbers, positive and negative numbers
included, can be obtained by adding subtotals (and multiplying
subproducts, respectively). These practices may be cast as axioms in
secondary mathematics. Then operations on polynomials are easily implied
justified by these "axioms" and the geometric introduction of column
methods for expanding a products of two sums. While set theory in pure
mathematics may imply the above axioms in university mathematics programs
instruction, an earlier and more accessible explanation based on easily accepted
and understood geometric and counting practices derivation of the above
axioms is possible at the high school for students heading for college programs
in science.
In Volume 2: Prep for Calculus
- What is the difference between saying A if B and saying A if and
only if B. Being aware of the difference will sharpen ye wits.
- What is a chain of reason?
-Are your arithmetic skills OK?
-Have words been missing in the introduction of algebra?
- Can ye talk about numbers & quantities varying apart from or before the
use of letters & functions?
- Do ye know about the forward & backward use of formulas?
-Contrapositive: is that backward use of A if B?
-What is a variable x? Answer before speaking of function f(x) = x.
-What a twist! There are no rules of algebra for subtraction and division. But
if you replace them by addition of -x and multiplication by 1/x, rules of
algebra (properties of arithmetic) can be used.
In Volume 3: Calculus Slowly?
-Why are slopes studied and polynomials factored in high school?
- Volume 3 suggests how to ease or delay algebra shock in
calculus *& beyond. In Calculus, derivatives and integrals introduced and defined by limits, but calculated
without when possible by using differentiation rules forwards and backwards. The
second site calculus section may help in differential calculus.
|
|
|
|