# Axis Y and X

##### Full Member
Hold on you're telling me too many things like I'm skilled in math ... one by one lemme understand

what do you mean by standard ? if something is standard then allowed in math to call it whatever ?!

what's confusing me why we are allowed to call them whatever we want? who said it's allowed in math ..?

#### Dr.Peterson

##### Elite Member
You can call a pair of axes anything you want. We customarily call them x and y when there is no reason to call them something else; but graphing is a tool you can use as you wish, not a tyrant that restricts what you can do. (That's true of all of math, actually.)

Often, the horizontal axis is used to represent an independent variable (for example, time), and the vertical axis is used to represent a dependent variable (say, temperature). Have you never seen graphs representing anything like that?

In abstract problems, we tend to call the independent variable x and the dependent variable y; but in applied problems, we use the natural names appropriate to the problem.

The real question is, why would you think this is not allowed? What would be the benefit of such a restriction?

When a teacher tells you to do something, go along with it, rather than acting like you know better than the teacher! Perhaps your experience is less than his.

• topsquark

#### JeffM

##### Elite Member
The letters that we use to stand for variables are ARBITRARY, and what a given letter represents varies from problem to problem. I believe that you have been told this before. This is one of the reasons that you should define your terms at the beginning of every problem.

It is a conventional to use x for the independent variable, and y as the dependent variable. And it is conventional to use the vertical axis for the dependent variable, and the horizontal axis for the independent variable. But no one is obligated to abide by these conventions.

• topsquark

#### Otis

##### Senior Member
… lemme …
Why are you allowed to use that word? Who said it's allowed?
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• • topsquark and Ryan$#### Ryan$

##### Full Member
to
Why are you allowed to use that word? Who said it's allowed?
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be more frankly , I don't know ! maybe that's the problem? I need to solve that struggle !!! while solving I face that struggle every thinking , could you help me to how should I think or actually why going along that approach "why it's allowed and why not" is a wrong approach while thinking ?! thanks alot

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##### Full Member
Hi guys, can I in mathematics determine where's my prime point (0,0,0) of Axis x,y,z to start? I mean lets assume I have triangle .... and I want to put it on Axis x,y,z ... , can I decide which corner of my triangle I would like to put my Axis of (x,y,z) to start with? if so why it's right?

#### lev888

##### Full Member
It's your triangle and your coordinate system. You can decide where to put the corners.

• mmm4444bot, topsquark and JeffM

#### lev888

##### Full Member
Let's say your house number is 20, your friend lives in 24. How many houses are between you and your friend? One - #22. Let's put the "origin" at the other end of the street. You are now in 15 and your friend is in 11. How many houses are between you and your friend? Still one. Now matter where you start house numbers the answer will remain the same.

• JeffM and topsquark

#### JeffM

##### Elite Member
Actually, I am going to take my life in my hands and disagree with Dr. Peterson.

The math that you are being taught is based on a set of axioms. Axioms are things that you accept as true on faith (or a "willing suspension of disbelief"), but all the rest of a system of mathematics is proved logically from those axioms. There is nothing that says you must accept those axioms. In that case, you are free to build a completely new mathematics developed logically from a different set of axioms.

The mathematics that you are being taught is based on axioms that are very extensively validated by experience in the real world. For example, one of its axioms is

$$\displaystyle \exists \text { no pair of elements of the set such that } a * b \ne b * a.$$

Experiment with a few hundred pairs of real numbers to see whether this axiom is ever inconsistent with experience. So we use the system based on the axiom above for real numbers.

But it is perfectly possible to develop a mathematical system based on an alternative axiom, namely

$$\displaystyle \exists \text { pairs of elements of the set such that } a * b \ne b * a.$$

Although the set involved is not that of real numbers, that axiom can be demonstrated as consistent with experience of sets involving some kinds of thing (but not real numbers).

So the mathematics that you are currently studying is based on axioms, which you are to assume are true, and theorems, which have been proved to be true if the axioms are true. There is no need to ask who says so. You are assuming that they are so. (And no one has found a real number for which they are not so.)

You are free to create a different mathematics (though it is likely to be completely useless in the world of experience). And to the extent that you accept the axioms and theorems of the real number system, you are free to create any assumptions that do not implicitly contradict the axioms and theorems of the real number system.

In the centigrade system of measuring temperature, 0 is the highest ambient temperature at which pure water freezes. In the Fahrenheit and Kelvin systems of measuring temperature, 0 is not the highest ambient temperature at which pure water freezes. In the different systems zero has a different physical meaning. Where you set the origin of a coordinate system is arbitrary.

Now Dr. Peterson gave you very good advice. When your teachers and texts say something is always true, just accept it and learn the mathematics that results from those statements. You are not going to learn anything of practical or theoretical use if you keep wondering whether it is true that 7*3 = 3*7. There may be alternative mathematics, but the mathematics that you are being taught, the mathematics of real numbers, is of major practical importance because it is what is consistent with quantities counted or measured in macroscopic, physical reality. 7 sets of 3 balls each add up to a total of 21 balls in all and so do 3 sets of 7 balls each.

You are wasting incredible mental energy asking why certain things are true when the process is about why some things are true if certain other things are true. It is simply stupid to ask why the certain other things are true. They are assumed to be universally true because no contrary example has ever been found.

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• topsquark