Question

Why is Epsilon used?

Answer 1

Hint: First, we need to know about the word Epsilon and what is Epsilon, and its uses in mathematics.
Since in mathematics the Epsilon is represented with the symbol $ \in $. Also, in Greek mathematics, they will represent the Epsilon as $\varepsilon $which is more similar.
But it is just not like any other mathematical representation of the variables $y,a,k$.

Complete step by step answer:
The word Epsilon is the Greek letter and it stands (which means) an arbitrary number (smallest possible numbers) and we use it in the algebraic inequality’s concepts.
We use Epsilon to denote the smallest quantity like a term which is taken as the zero in some limit.
As the symbol, we can see that Epsilon $\varepsilon $,
Thus, Epsilon is the letter in the concept of making the predicate while dealing with the limits and which is always the smallest value.
And we should be careful that this symbol of the Epsilon should not be confused with the set symbol that we used to denote the contained subset.
We know that in the set theory we used the symbol for the contains or belongs to is $ \in $ (same as Epsilon but which is called as belongs to in the set theory), which states that a subset belongs to the set.
Example take $a \in \{ 1,2\} $then it means that the variable $a$ belongs to the set of $\{ 1,2\} $

Note: We use various symbols to denote the Epsilon values too because Epsilon has no interest in the meaning of its own like other mathematical symbols like $\pi $(pi) and it has the value $3.14$.
Also, the symbol $e$ and has value $2.71828$. But Epsilon has no value.
Like as belongs to symbol, there is also the symbol called does not belongs to, which is represented as ($ \notin $)$a \notin \{ 1,2\} $where it does not belong to the set $\{ 1,2\} $