What is the difference between 2x and 2n?

Answer 1

This depends entirely on the context, but usually, an x denotes an unknown amount in an expression, while n denotes where a term is in a sequence.

Examples:

I have x amount of apples. My sister has twice that amount. How many does she have?

2x

A sequence goes 1,2,3,4... etc. The term "n" is a certain amount. Which term is twice that amount?

2n

This is how they are usually used, but they can also be interchangeable if you want to use them interchangeably. x and n both just mean "an unknown value".