In Maths, what does Un mean, where n is subscript (the opposite of the powers, below the u)?

Question

Help, i don't know what it meant. I used to think it was a way to write powers... but now i know its not, im quite confused.... :(

Answer 1

n simply tells you the position.
For example the sequence 2, 4, 6, 8, ...
we can write An = 2n
so A1 = 2 meaning the first term in the sequence is 2
A2 = 4 (A2 means second number)
So A50 means tell me what is the 50th number.

Answer 2

Subscripts are usually used when you have several of something and you don't want to waste a letter on each. Instead of x,y,z,w, why not x1,x2,x3,x4. That way you still have a spare y or z if you need it.

Answer 3

The n is just an indexing operation.

Doug