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# Reference Material

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## Reference Material

### INTRODUCTION:

Hello! You have reached the “Reference Material” page. This page is a list posts that have explained things well and are good to look back at for future posts and for reference material.

I redid this to try to make it easier to access/refer back to.  This is really NinjaDevo's post. He did a fantastic job organising it for the forum.  He no longer has time to upkeep it so I have copied it over into my thread so that I can edit it.

Here is the original 2 posts by

This page is broken down into different sections as to try to make it easier to refer back to. For the most part, the topics are organized by “grade levels” of mathematics (like Algebra, Trigonometry, Calculus, etc.)

Remember, good manners are always important and very much appreciated!

http://web2.0calc.com/questions/good-manners-are-always-important_2

Without further a due, let’s dive right  in!

### Using the web2 calc:

• How to use the web2 calc for different things in physics like electron mass/atomic mass:

http://web2.0calc.com/questions/new-calculator-option

• Converting measurements on the web2 calc, two different methods:

http://web2.0calc.com/questions/how-to-convert-486mm-to-m#r2

http://web2.0calc.com/questions/1505-91-convert-unit-of-measurement#r2

• Absolute values on the web2 calc:

http://web2.0calc.com/questions/how-do-you-do-an-absolute-value

Inputting inverse trig

http://web2.0calc.com/questions/how-do-i-use-the-trig-inverse-keys

Integrals and Differentials on the Web2 calc.

http://web2.0calc.com/questions/what-is-the-calculator-s-exact-syntax-for-integration-and-derivatives

### HOMEWORK SITES

Review on Mathopolis homework site

http://web2.0calc.com/questions/mathopolis-review

and here is the actual Mathopolis site

http://www.mathopolis.com/index.php

Home work sites in general

http://web2.0calc.com/questions/whats-the-best-math-hw-site

Practice site - Varied questions.  Looks good.  Recomended by DragonSlayer 9/2/15

An another:   mathwarehouse.com

More have been added here by Eloise1st      (6/6/15)

http://web2.0calc.com/questions/do-anybody-know-some-websites-i-can-get-on-to-study-my-math-sol#r3

### - and calculator type resources    (includes presentation resources)

Latex Converter.

http://www.imatheq.com/imatheq/com/imatheq/math-equation-editor-latex-mathml.html

(I do not know how good this is - I have not used it myself yet.)   Dec18

Extensive Virtual Maths Keyboard

http://usefulwebtool.com/en/math-keyboard.php

Wolfram Alpha

This is an online computational knowledge engine that is used heavily by many mathematicians and students.

https://www.wolframalpha.com/

Desmos is a beautiful, easy to use, online 2D graphing calculator

https://www.desmos.com/calculator

High Precision 3D Equations plotter.   This is a downloadable resource and includes a free version.

http://www.runiter.com/graphing-calculator/

Equation solver        (found by Solveit)

Calculator for linear regression (suggested by Alan)

http://www.alcula.com/calculators/statistics/linear-regression

z score probabilities - this is great

http://davidmlane.com/hyperstat/z_table.html

Another Stats calculator - More versatile than the first     (Teach yourself Stats site!)

http://stattrek.com/online-calculator/normal.aspx

http://stattrek.com/online-calculator/binomial.aspx

http://www.danielsoper.com/statcalc3/calc.aspx?id=70

Line of best fit calculator

http://knowpapa.com/trend-line/

Gambling probability calculator - Lottery, Keno etc

http://www.easysurf.cc/lotodd.htm

General Statistics site - with its own forum.   I found this site very helpful  (Melody 30/7/15)

Binomial Probability Calculator

https://stattrek.com/online-calculator/binomial.aspx

Commercial Mathematics

This calculator that is dedicated to calculating bond prices.

http://www.investopedia.com/calculator/bondprice.aspx

https://arachnoid.com/finance/index.html

Calculus

http://www.emathhelp.net/calculators/calculus-1/derivative-calculator/?f=sqrt%281-x^2%29&order=1&var=&px=&steps=on

Make a graph! (recommended by Melody and CPhill)

https://www.desmos.com/calculator

https://graphsketch.com/                  (used by Sir-Emo-Chappington) 2D graphing program with some flexible features (suggested by Alan)

Look at this thread for discussion

http://web2.0calc.com/questions/how-do-you-find-out-the-soloutions-of-cubic-equations-without-a-calculator

3D graphing programs

http://web.monroecc.edu/manila/webfiles/calcNSF/JavaCode/CalcPlot3D.htm

Great math materials/explanations:

http://www.mathsisfun.com/

Conversion web page:

http://www.convert-me.com/en/convert/volume/

Pascal's triangle - Examination of it.

http://ptri1.tripod.com/

GeoGebra, math software and tons of math materials!

http://www.geogebra.org/cms/en/

Equations with GeoGebra

http://web2.0calc.com/questions/given-the-system-of-equations-y-x-2-4x-x-4-the-number-of-points-of-intersection-is

Venn Diagram maker

http://www.softschools.com/math/venn_diagram/venn_diagram_maker/

Simultaneous Equation solver (with steps) for Gaussian Elimination (Matrix soln)

OEIS (On-line encyclopedia of Integer sequences) Can’t find a pattern between a few numbers? Try out this website!

http://oeis.org/

### Basic Maths Concepts:

Multiplying a multidigit number by a single digit

Multiplying a multidigit number by another multidigit number

Rounding decimal numbers - great clip

Detrermining factors for a large number

Percent practice applet - A little practice site

http://tube.geogebra.org/m/498041

Finding percent of a number (or money)

http://web2.0calc.com/questions/is-there-a-fix-way-where-i-can-memorize-the-time-table-from-1-to-12-time-table

What does dividing by a fraction mean?

Long division:

http://www.mathsonline.org/pages/divisionSolution.html?1234&12&0&1

http://www.mathsisfun.com/long_division.html

Postive and negative numbers:

http://web2.0calc.com/questions/positive-and-negative-numbers-directed-numbers

Addition and subtraction of direct numbers:

http://web2.0calc.com/questions/it-just-doesn-t-make-sense-to-me

Dividing whole numbers by fractions:

http://web2.0calc.com/questions/dividing-whole-numbers-by-fractions

How to type in a fractions on this calculator:

http://web2.0calc.com/questions/how-do-i-type-in-fractions#r2

What happens when you divide by zero?

http://web2.0calc.com/questions/what-happens-when-you-divide-by-zero

http://web2.0calc.com/questions/what-happens-if-you-divide-by-0#r3

Factoring by hand and using the Web2calc

http://web2.0calc.com/questions/prime-factorization-of-405

What do 7!  and !7   mean?

http://web2.0calc.com/questions/what-does-the-meaan

Why does 0!=1

http://web2.0calc.com/questions/why-is-0-1

What is pi

http://web2.0calc.com/questions/what-does-pi-equal_1

What is Phi ( φ )?       Thanks Chris

Estimating square roots with the Newton method:

http://web2.0calc.com/questions/hi-i-want-to-know-how-to-solve-somthing-like-nbsp#r1

Square root in answer verses introduced square root.

Averages and rounding (question)

http://web2.0calc.com/questions/tom-took-five-math-tests-and-got-an-integer-score-on-each-of-them-he-never-scored-higher-than-90-and-his-lowest-score-was-the-fourth-test

Working with ratios.    Finding a part when given the whole.

http://web2.0calc.com/questions/in-a-school-1620-pupils-the-ratio-of-boys-to-girls-is-4-5-what-is-the-nunber-of-girls-in-the-school

Modulo Arithmetic {nl}

http://web2.0calc.com/questions/64-235-mod-391#r0

This modulo question is fabulous so is Alan's answer :)

This is an interesting question to - Great answers from CPhill and Bertie

http://web2.0calc.com/questions/show-that-7-p-6-p-1-for-p-3-prime-is-multiple-of-43

http://web2.0calc.com/questions/page/1927

http://web2.0calc.com/questions/how-come-30-99-61-100-is-divisible-by-31#r4

Diophantine equation - modular arithemtic     - Melody and CPhill    (2/7/15)

http://web2.0calc.com/questions/a-school-orders-99-textbooks-all-for-the-same-price-when-the-bill-for-the-total-order-comes-the-first-and-last-digits-are-obscured-and-t

Lots of Number theory questions on this page (Questions provided by Mellie)

http://web2.0calc.com/questions/page/1895

Hexidecimal numbers and a look at different bases.

http://web2.0calc.com/questions/somewhere-i-saw-wrote-hex-on-calculator-what-dies-it-means#rr2

Continuous Compounding

http://web2.0calc.com/questions/find-the-accumulated-value-of-an-investment-of-15-000-for-5-years-at-an-interest-rate-of-7-if-the-money-is-compounded-continuously

Finding the LCM and HCF of big numbers.  Nifty formula and demo by Heureka.

http://web2.0calc.com/questions/what-is-the-lcm-of-8847-and-2532

How do you simplify a radical?

Working in different bases.   There are a lot of ineresting questions on pags 1843  and 1844

The number of positive integers less than or equal to na that are relatively prime to n

Euler's Totient Function

http://web2.0calc.com/questions/for-a-positive-integer-n-phi-n-denotes-the-number-of-positive-integers-less-than-or-equal-to-n-that-are-relatively-prime-to-n-wh

http://web2.0calc.com/questions/for-a-positive-integer-n-phi-n-denotes-the-number-of-positive-integers-less-than-or-equal-to-n-that-are-relatively-prime-to-n

There are 5 questions number related on this page.  All posted by "mellie"

### ALGEBRA:

Introduction to pronumerals:

Equation solver        (found by Solveit)

Finding the 2 numbers - this post is not comprehensive it is just a start.

http://web2.0calc.com/questions/i-need-help-trying-to-get-a-factor-that-equals-to-a-postitive-11-and-a-postitive-30

Determining a function from a set of ordered pairs when it is not linear.  (geno3141)

Solving a more difficult algebra problem:

http://web2.0calc.com/questions/solve-for-x-x-6-5-x

A page explaining how to solve inequalities:

http://www.mathsisfun.com/algebra/inequality-solving.html

Using polynomial graphs to solve polynomial inequalities

Youtube clip explaining how to factor trinomials using the grouping method:

Graphing log functions on the web2 calculator:

http://web2.0calc.com/questions/how-do-you-insert-log-into-the-graph-on-this-website

Negative indices and negative exponets (a great explanation by Melody)

http://web2.0calc.com/questions/indices-especially-negative-indices

Advanced Algebra - Example of Remainder Theorem with full explanation.

Polynomial Division   ( I know there is another post on this in here but i can't find it) :(

Also includes Horner's Method

## Co-ordinate Geometry

Interactive game for practicing co-ordinates

http://web2.0calc.com/questions/number-plane-co-ordinates-interactive-practice-for-beginners

Interactive site for practicing finding gradients between two points on a number plane

Domain and Range - Exponential Functions  {nl}http://web2.0calc.com/questions/would-i-be-able-to-get-the-domainand-range-from-a-function-or-does-it-have-to-be-from-a-graph

Finding root using secant method.   Thanks Alan

http://web2.0calc.com/questions/find-the-roots-of-the-equation-x2-4x-5-0-the-secant-method

Interpreting polynomial graphs.         Melody

http://web2.0calc.com/questions/how-do-you-find-a-power-function-that-is-graphed

Using polynomial graphs to solve polynomial inequalities

Some theory behind functions and curve sketching (asymptotes and roots and y intercepts)

CPhill     (11/6/15)                                These are on page 1854 approx

http://web2.0calc.com/questions/write-an-equation-for-a-rational-function-with-vertical-asymptotes-at-x-4-and-x-6-x-intercepts-at-x-4-and-x-2-horizontal-asymptote

http://web2.0calc.com/questions/write-an-equation-for-a-rational-function-with-vertical-asymptotes-at-x-2-and-x-6-x-intercepts-at-x-1-and-x-5-y-intercept-at-2-y

Graphing Functions using transformations from the parent function           Melody

http://web2.0calc.com/questions/how-do-you-describe-the-transformations-from-the-parent-graph-of-x-sqrt-x

Hyperbola Questions

http://web2.0calc.com/questions/the-equation-of-the-hyperbola-that-has-a-center-at-1-2-a-focus-at-4-2-and-a-vertex-at-3-2-is-frac-x-c-2-a-2-frac-y#r0

### GEOMETRY:

Understanding conics, focus, directric, etc, with interactive graphing:

http://www.intmath.com/plane-analytic-geometry/4-parabola.php

Angle with degrees, minutes, and seconds:

http://web2.0calc.com/questions/hey-i-need-to-find-a-side-of-a-triangle-but-the-angle-is-using-degrees-minutes-seconds-and-your-calculator-does-not-do-them

Segment of a circle:

http://web2.0calc.com/questions/how-do-i-find-the-length-of-a-segment-of-a-circle#r2

Surface area of a cylinder:

http://web2.0calc.com/questions/what-is-the-surface-are-of-a-cylinder-with-r-8-h-4#r1

Volume of a Shere - Really interesting analysis

A YouTube clip that shows measuring volume using displacement:

Some discussions/explainations of pi:

http://web2.0calc.com/questions/what-is-the-value-of-pi#r1

### PROBABILITY AND STATISTICS:

How to remember mean mode and median

http://web2.0calc.com/questions/how-do-you-memorize-mean-median-and-mode-quickly#r3

Standard deviation

http://web2.0calc.com/questions/how-do-you-find-standard-deviation_1

Finding a confidence interval for a Bernoulli distributions

http://web2.0calc.com/questions/in-an-experiment-using-30-mice-the-sample-proportion-of-the-mice-that-gained-weight-after-a-drug-injection-is-0-65-what-is-the-99-7-confi

Determining the least squares regression line from raw data.

Why is 0!=1 ?   Factorials  and gamma functions explained

I really enjoyed the video clip.

It starts at the very beginning - explaining what factorial means.

Then if progresses to gamma functions.

so there is something for almost every one.

ALSO

The is a clip from the    Numberphile website   I'll bet their other clips are just as interesting. The probabilities of Poker

http://en.wikipedia.org/wiki/Poker_probability

Here are a whole heap of probability threads that I have been collecting

Expected Value

Interesting alternate to Venn diagram

http://web2.0calc.com/questions/i-think-this-is-a-mutually-exclusive-question

Constructing a confidence interval           Alan (20/6/15)

http://web2.0calc.com/questions/the-random-sample-shown-below-was-selected-from-a-normal-distribution-3-3-3-9-10-8-a-construct-a-95-confidence-interval-for-the-populatio

### TRIGONOMETRY:

Inverse trig on the web2 calculator:

http://web2.0calc.com/questions/how-can-i-put-tan-minus-in-the-calculator

How do you choose the correct trigonometric ratio (sin, cos or tan) to use?

Graphing complicated trig functions:

http://web2.0calc.com/questions/graphing-trig-functions_1#rr2

http://web2.0calc.com/questions/can-anyone-remember-the-formulas-of-period-phase-shift-and-range-of-the-sin-function#r5

### CALCULUS:

Introductory calculus:

http://web2.0calc.com/questions/determine-the-average-rate-of-change-of-the-function-between-the-given-values-of-the-variable_1#r1

Problem chain rule question.  {nl}http://web2.0calc.com/questions/a-street-light-is-on-top-of-a-6m-pole

Implicit Differentiation

http://web2.0calc.com/questions/using-implicit-differentiation-find-the-equation-of-the-tangent-line-to-the-given-curve-at-the-given-point-3x2y2-3y-17-5x-14-at-1

PHYSICS:

Electricity  Energy = Power/time             (12/8/15)

COMPLEX NUMBERS:

Polar co-ordinate proof.

Use sinθ=1/2i(e^(iθ)-e^(-iθ))  To obtain the identity  sin^5θ=1/16(sin5θ−5sin3θ +10sinθ)

http://web2.0calc.com/questions/trigonometric-identity

Cartesian to Polar coordinates and vise versa.  Lots of questions on page 1815

http://web2.0calc.com/questions/page/1815

Vector in polar form multiplication (Complex numbers)             Alan and Bertie  16/6/15

http://web2.0calc.com/questions/100angle30-10angle-165#r8

MISC:

What time is it around the globe?

http://web2.0calc.com/questions/world-time-map

Information for new people:

http://web2.0calc.com/questions/information-for-new-people

### WEBSITE TIPS/TRICKS:

One of reinout_g's tricks:

http://web2.0calc.com/questions/found-something-that-makes-life-a-lot-easier

How do I upload an image?

Searching with keywords:

http://web2.0calc.com/questions/how-to-search-use-keywords-to-find-what-you-want

LaTex (a format that can be used when answering questions on this forum) This can be confusing when you first look at it. Here’s some posts on how to use LaTex:

http://web2.0calc.com/questions/test_6

http://web2.0calc.com/questions/latex

\$\$\$\$

Here's some funner links/topics to finish up the post.

A math-game website:

http://www.cut-the-knot.org/

Why math is so hard:

http://web2.0calc.com/questions/why-does-math-have-to-be-hard-i-wish-it-was-slightly-simpler-and-then-i-would-love-math-i-do-like-math-though

http://web2.0calc.com/questions/why-is-math-so-hard#r10239

Basic maths lectures - The one I watched was great.  There are many

Oct 18, 2014
edited by Melody  Feb 12, 2016
edited by Melody  Feb 12, 2016
edited by Melody  Apr 5, 2017
edited by Melody  Jun 17, 2017
edited by Melody  Dec 25, 2018
edited by Melody  Dec 25, 2018
edited by Melody  Apr 24, 2019

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Probability.

B***s and Boxes   (July 2016)

http://web2.0calc.com/questions/plz-help-me-fast

Using Boolean contour mapping.

https://web2.0calc.com/questions/probability-and-geometry

Jul 28, 2016
edited by Melody  Sep 29, 2017
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Another good list of statistics calculators is

http://www.emathhelp.net/calculators/probability-statistics/

Commercial mathematics calculator

https://arachnoid.com/finance/

Aug 14, 2016
edited by Melody  Oct 22, 2017
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Understanding Parabolas:

OfficialBubbleTanks ( a member here in Nov17) Made this interactive Desmos graph so that people can learn to understand parabolas better. This is a  great tool I think :)

Thanks OBT :)

Or if you want to skip straight to the graher:

https://www.desmos.com/calculator/7eoswakc2i

Nov 7, 2017
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Hello people! I am OBT, the person Melody was talking about.

I wanted to say that I have updated my graph by adding a discriminant solver!

https://www.desmos.com/calculator/2kgbw2svfn

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Thanks OBT

Melody  Jan 24, 2018
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TRIGONOMETRY

A trick for remembering the exact values of  sin and cos 0, 30, 45, 60, and 90 degrees.

Many students and teachers could make good use of this!

Thanks XSquaredFactor :)

Jan 24, 2018
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The secrets of   PASCAL'S TRIANGLE

GYanggg  has provided us with this great explantaion / examination of Pascal's triangle.

https://web2.0calc.com/questions/the-pascal-s-triangle

Thanks Gavin :)

Jun 26, 2018
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Here is a trapezoid soving calculator that was used for this question.