# need help understanding: if I have X then by superposition I can do X=x1+x2+x3+x4+x5+x6+x7+x8.....+xn

##### Junior Member
Hi guys ! before making this thread I really thought multiple times for posting it or not but it's really something in my mind harassing me about what I'm going to ask.

What does quantity mean in math? why I'm asking about this because while I solving problems I always find obstacles about connections between quantities .. in other words for instance to find the value of something I may do sum of superposition on other things to find that value ! and doing that sum needs to understand what does quantity is !

#### Ryan$##### Junior Member Quantity is how many you have. For example: I have 3-$5bills, I have 7 bananas, I owe you 3 oranges, I have 9x's etc...
Alright I'm with you, but once I start solving any problem in math specifically when there's something that equals a collections of other things then I start imagine that their "amounts" are related to each other and they are not separated (i.e words imagining the amounts as continues things) !

I will try to be more dramatically concrete about quantity term.

thanks you anyway mate!!

#### Jomo

##### Elite Member
Alright I'm with you, but once I start solving any problem in math specifically when there's something that equals a collections of other things then I start imagine that their "amounts" are related to each other and they are not separated (i.e words imagining the amounts as continues things) !

I will try to be more dramatically concrete about quantity term.

thanks you anyway mate!!
You put amounts in quotation marks but are defining quantity. But that is OK.

something that equals a collections of other things then I start imagine that their "amounts" are related to each other and they are not separated.

I am not exactly sure what their means but I will try to address your concerns. I think by their you really mean to use a singular proverb not plural.

I guess you are thinking about something like x = $17.50y +$33z, where x is your total salary, y is the number of hours you worked at $17.50/hr and z is similarly defined. Yes, x is an amount! Its units are dollars. x IS relates to y and z. It is possible that y and z are separated but they are related to x. If you earn$17.50/hr and your mate earns $33/hr and your hours at work never cause any problems, then y and z are not related. #### Ryan$

##### Junior Member
You put amounts in quotation marks but are defining quantity. But that is OK.

something that equals a collections of other things then I start imagine that their "amounts" are related to each other and they are not separated.

I am not exactly sure what their means but I will try to address your concerns. I think by their you really mean to use a singular proverb not plural.

##### Junior Member
Can you please provide an example of this phenomenon?
Yes sorry for not clearing it out.

lets assume I have 7 potatoes which each of them weight 1kl , then if x is the total weight and xi the the weight of one potato ,
so the total weight = sum of all xi that I've i.e X=x1+x2+x3+...+x7 (that's called superposition)

##### Junior Member
Hi guys, in brief , By superposition I can implicitly manage all of the problems, I mean I can always look at problem in its general regardless of +/-/* arithmetic math manipulation, what's confusing me is, how do I remember that always?! I mean lets assume I have one orange+one orange=two orange , but "two orange" by superposition I can say it's also generally orange .. so anyone can help me how should I visualize the superposition of things among things? it's like something magic that convert all the collection to one specific thing with the same type of the elements of the collections ..

thanks

#### tkhunny

##### Moderator
Staff member
That's not even a question.

Why not ponder multiplication? one orange * one orange = ?? Is THAT still "generally orange"? Does it even exist?
Are you talking about linear systems?
Are you talking about quantum systems in multiple, simultaneous states?
Are you talking about photo-superposition in photography?
Are you talking about a new layer of substrate in a geological structure?

Why would you EXPECT to be able to "visualize the superposition of things among things"? That is FAR to vague for any such expectation.

Distinct objects may be related. Does it have ANYTHING to do with "superposition"? Is that the same thing as simply grouping?

#### Otis

##### Senior Member
Your English is like water vapor, to me. I know something is there; I just can't see it.

Can you post a link to what you're looking at, so people can see it?

##### Junior Member
what do you mean by "is closed under addition " ?!

#### tkhunny

##### Moderator
Staff member
Closed Under Addition: Add things and don't get something else.

Integer + Integer ==> Integer -- Closed
Integer / Integer ==> Might be an Integer, Might be a Rational Number, might not exist. -- Not Closed
Orange + Orange ==> Orange -- They don't magically turn into Soursops. -- Closed

#### Otis

##### Senior Member
what do you mean by "is closed under addition" ?!
A set is "closed under addition" if adding any elements in the set results in another element in the set.

If you add Integers together, you are guaranteed to get another Integer.

We can have closure with other operations, too. The set of Integers is closed under addition, subtraction, multiplication and exponentiation.

Another example: The set of positive Integers is closed under addition but not subtraction.

1 - 2 = -1

Subtraction with two elements of the set yielded an element that is not in the set.