John H.

asked • 09/20/17

generating 'n' number of variables?

I want to make an indeterminate number of variables for an equation...i.e. I want to generate 'n' number of variables 'X' where X1, X2... Xn are all different variables not dependent upon one another. How would I write this in formulaic terms?

Closest I've come to is summation notation
n
∑Xi = X1+X2+...Xn
i,1
but I want each of X1, X2 etc. to be their own independant variable, and not be based off some table (i). i.e. X1= a, X2= b, etc.
 
 

1 Expert Answer

By:

Kenneth S. answered • 09/21/17

Tutor
4.8 (62)

Expert Help in Algebra/Trig/(Pre)calculus to Guarantee Success in 2018

See tutors like this
See tutors like this
Generally, when there are to be n elements in a set, but n (number of them) is not fixed, those elements can be named xi and subscript i can take on any integer value from 1 to n.
 
What do you want to do with them? You correctly understand how to form their sum, using Sigma notation.
If you wish to refer to variable #k to obtain its value, you just write xk.
 
Your use of the word GENERATE is undefined and that may be the source of some of your internal confusion.
Upvote • 0 Downvote
More
Report

John H.

ok... well for this portion I am basically wanting to denote a sum of a string of items that would total, say 50... but the items would be in groups (variables) like, say I have 50 fruits, but the fruits I have are apples, oranges, and watermelons. then, saying I still have that 50 fruit total but I now have the groups of bananas, and strawberries. the type of fruit (variable) wouldn't matter for the total, but the amount of each fruit would be independant of the others (aside from their total having to be 50)
 
so basically...
n
∑Xi = 50
i=1
 
where Xi remains undefined for each value up to n, to be defined in later formulae...
i.e.
n
∑Xi = 50                 : X1+X2+... Xn= 50
i=1
then:
2
∑Xi = 10                 : X1+X2=10
i=1
 
n
∑Xi = 40                 : X3+X4+... Xn =40
i=3
 
3
∑Xi = 25                 : X2+X3 =25
i=2
 
I really don't know how else to explain it without going over a multi page formula and it's nuances... basically it's just I need a way to say "these three variables can add up to 50, however these 5 variables can also add up to 50, and these 'n' variables can add to a total of 50"
Report

09/21/17

John H.

just thought of a way to make my needs more clear (or muddled depending on how you look at it). I need:

n
∑(X+n)i = 50
i=1
 
where 'n' is the primary variable, but once determined you get an output of 'n' number of variables which 'n' is added to each variable to form a total sum of 50. In the above case, assuming that 'X' must be a whole integer, this would limit 'n' to being 6 or less, yet each instance of 'X' could still be any undefined number.
Report

09/21/17

Kenneth S.

It sounds to me as if you might be wanting a matrix, where different columns corresponds to different fruits.
I do suggest that you confer with your teacher, if this is related to a class that you're taking. You need to be able to bounce your ideas off another person, and for each of you to continue to inquire of the other until you both come to an understanding.
Report

09/21/17

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.