What does an with a subscript n mean in mathematical equations?

  • Thread starter Thread starter teng125
  • Start date Start date
AI Thread Summary
In mathematical equations, a letter with a subscript "n" typically denotes a specific value or term in a sequence or set of values. This notation helps differentiate between multiple values, such as components of a vector labeled as a1, a2, and a3. The subscript "n" is commonly used to represent the position of a term in a sequence, where "n" corresponds to positive integers. This distinction is crucial as it differentiates sequences from functions, with sequences specifically defined over positive integers. Understanding this notation is essential for interpreting mathematical expressions accurately.
teng125
Messages
416
Reaction score
0
any alphebet with a small n??

does snybody knowswat is the meaning of the eqn when there is any alphebet with a small n underneath or next to it?
 
Physics news on Phys.org
teng125 said:
does snybody knowswat is the meaning of the eqn when there is any alphebet with a small n underneath or next to it?
1. Please write in English, and not in Gibberish
2. What are you asking about? Indices like in a_{n}?
 
yaya...that's what i mean
 
Arildno, there are an awful lot of people here for whom English is a difficult language! Cut them a little slack.

teng125, and alphabetical character (to make arildno happy) with a subscript n, normally, is just a way 9f distinguishing among many different values. One application is with vectors where we may label the "x","y", and "z" components of the vector a by a1, a2, a3.

Another important application, which is likely to be what you are looking at, is to label numbers in sequences. The only difference between a sequence and a function is that the "domain" of a sequence is the positive integers: 1,2, 3, etc. A standard way to distinguish them is to use x for a "real variable" and n for a "positive integer variable". Some texts actually use a(n) for a sequence (more correctly the nth term in the sequence) but it is more traditional to use a subscript: an.
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Essentially I just have this problem that I'm stuck on, on a sheet about complex numbers: Show that, for ##|r|<1,## $$1+r\cos(x)+r^2\cos(2x)+r^3\cos(3x)...=\frac{1-r\cos(x)}{1-2r\cos(x)+r^2}$$ My first thought was to express it as a geometric series, where the real part of the sum of the series would be the series you see above: $$1+re^{ix}+r^2e^{2ix}+r^3e^{3ix}...$$ The sum of this series is just: $$\frac{(re^{ix})^n-1}{re^{ix} - 1}$$ I'm having some trouble trying to figure out what to...

Similar threads

Back
Top