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YOU are better than YOU think. Show yourself how:
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On the phone with a classmate or tutor,
or twiddla or
groupboard to write &
draw with each other on art, math & science etc.
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
Do not leave here without it - Logic
mastery will develops critical thinking, improve reading and writing,
and give a firmer base for work and studies at many levels. Good luck.
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Caution: Site advice is approximately
correct, for some circumstances, not all. Site How-TOs are logically
developed, but not tried and tested. That leaves room for thought and
refinement.. |
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After logic,
(a) continue reading Three
Skills for Algebra, chapters 8 to 14 and do so alongside site area on solving
linear2007 Equations ; or (b) see this calculus
starter lesson and Volume 3, Why
Slopes & More Math, chapters 2 to 6;
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.
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Slopes with Units - Rates of Change
For a straight line graph of a first quantity Q1 versus a
second quantity Q2, the slope
| m = |
change in Q1
change in Q2 |
= |
DQ1
DQ2 |
= |
rise
run |
· |
|
The units of the slope m are therefore given by
|
units of Q1
units of Q2 |
= |
units of the rise
units of the run |
|
|
That is, the units of slope is the ratio given by the unit of
rise (vertical axis) over the units of run (the horizontal axis).
Examples of ratios of units that often occur are:
|
$
kg |
, |
km
|
, |
km
hr |
, |
miles
hr |
,
1, etc. |
|
Observe that when Q1 and Q2 are measured
with the same units, the slope m has no units. It is given by a (real)
number. An example follows. The purpose of the unit 1 in the previous
list is to be a reminder of this. We may say that a real number has the unit 1
to include numbers in any discussion of quantities. Alternatively, we may say,
as convenient, that real numbers are without units. See next example.
Improper Units
The unit 1 is an improper unit. The units 1 radian = 1. So
the degree = [(p)/180] and the one percentage 1.0% =
[1/100] are further examples of improper units, that is units that are multiples
of real numbers. (The discussion of improper units is unique to this author.
Units in computations have been a concern for chemists and physicists but
not so far for mathematicians. The codification of mathematics needs to be
extended to include units as a service to other disciplines.
Cost Versus Quantity -Rates
The metric BWGZ gravel supply business charges the amount
|
C = $20.00 + w· |
$15.00 50 kg |
|
|
for each amount w of gravel purchased. (For each order of gravel, the BWGZ gravel company charges $0.30
per kilogram plus $20.00. The latter could be a handling
or order setup charge.)
The graph of
cost or price C versus the amount w follows.

The slope of this straight-line graph is
|
m = |
$15.00 50 kg |
= |
$30.00 100 kg |
= 0.30 |
$ kg |
|
|
There are several possible ways to write m. Pick the one
you like or favor.
For w = 2000 lbs of gravel, the cost would be
|
|
|
|
$20.00 + 2000 lbs· |
$15.00 50 kg |
|
| |
|
|
$20.00 + 2000 · |
15.00 50 |
$· |
lbs kg |
|
| |
|
|
$20.00 + 2000 · |
15.00 50 |
$· |
lbs 2.2046 lbs |
|
| |
|
|
$20.00 + |
æ ç
è
|
2000· |
15.00 50
|
· |
1 2.2046
|
ö ÷
ø
|
$ |
| |
|
| $20.00 + $272.16 = $292.16 |
|
|
since 1 kg = 2.2046 lbs at the surface of the earth.
FOOTNOTE: At the earth surface, a one pound mass and one pound
weight are identical measures of material. There is a distinction
between mass and weight that has to be considered for calculations
away from the earth surface. Students of physics should know
why.
In computations, we follow the
convention that units can appear before or after the number
in it. In contrast, in the presentation of results, the
placement of the unit before or after depends on
grammatical or cultural preferences of a cosmetic nature.
| |
www.whyslopes.com
Fractions, Ratios, Units, Rates
& Proportionality
Fraction
Starter Lesson
(simplify, multiply, divide & then add or subtract)
An Alternative Starter
Lesson
(take your pick, or try both)
Area Intro Fraction Starter Lesson A Fraction Starter Lesson B 1 What is a Fraction 2 Multiplication I 3 Multiplication II 4 Multiplication III 5 Equivalent Fractions 6. Mixed Numbers 7 Comparison 8 Addition I 9 Addition II 10 Addition III 11 Multiplication IV 12 Division 13 Two Term Ratios 14 Implied Ratios 15 Multiple Ratios 16 Units in Arithmetic 16 Longer Explanation 16 Change Units 16 Products of Quantities 16. Fractions with Units 16. Division+Reciprocals 17 Proportionality 17 Examples 18 Rates & Slopes EGs 18 Constant Rate 18 Varying Rate 18 Velocity Calc., EGs 18 Changing Units 18 Slopes and Units 18 Slopes, No Units 19 RealPlayer Videos Links
Arithmetic Videos - Real Player Format
Decimal Addition
Methods
Decimal
Subtraction Methods
Decimal
Multiplication Methods
Decimal Division
Methods
Fractions
Primes
Greatest Common
Divisors
Least Common Multiples
Square Root
Simplification
Area Content Summary
- Fraction Starter Lesson
- Real Player Videos on Operations with Primes and
Fractions
- Continuous Ruler & Line Segment
model for fractions and operations on fractions - Number Theory Area
points to the general model.
- Distinction between Ratios and Fractions, a nuance:
While binary ratios a:b may be identified with a fraction, triple
ratios a:b:c and further multiple ratios cannot.
- Saying how to add and subtract like monomials in
units and their powers, and saying how multiply and divide like and
unlike monomials leads to fraction like expressions involving units
and a framework for discussion rates - ratios of quantities - a
framework for handling proportionality constants, and framework for
carrying units through calculation in quantitative disciplines
Hint: See site area on solving linear equations to strengthen
fraction sense and algebra skills together. Good luck.
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