# Thread: proof of a theorem

1. ## proof of a theorem

Theorem states:
Note that a (sub n) is a constant sequence.
Suppose a (sub n) = a for all n greater than or equal to 1.
Then lim a (sub n) as n approaches infinity = a.

I need to prove this.

2. Originally Posted by Carol
Theorem states:
Note that a (sub n) is a constant sequence.
Suppose a (sub n) = a for all n greater than or equal to 1.
Then lim a (sub n) as n approaches infinity = a.

I need to prove this.
Is it true that $|a_n - a|<\epsilon$?

3. Originally Posted by Carol
Theorem states:
Note that a (sub n) is a constant sequence.
Suppose a (sub n) = a for all n greater than or equal to 1.
Then lim a (sub n) as n approaches infinity = a.

I need to prove this.
you need to use the definition of the limit for a sequence to show that $\lim_{n \to \infty}a_n = a$

that is, you must show that: for every $\epsilon > 0$, there exists an $N \in \mathbb{N}$ such that $n > N$ implies $|a_n - a|< \epsilon$