Is this a regular language? Number of a's greater than $k$

Question

Prove/disprove:

$L = \{ w \mid |w|_a \geq 2k \}$, where $\Sigma = \{ a,b\}$ and $k$ is a constant, is a regular language.

Intuitively I am saying yes, it is a regular language. But I don't seem to find a regular expression for it. Any help would be appreciated

Answer 1

(Since k is constant...) b*ab*a...b*a(a|b)* where 2k b*a is in the expression.

(I don't know how to format this neatly in LaTeX...)