Answer:
y = 4 * sec x - 1
Explanation:
From looking at the graph we can safely determine it's either CSC x or SEC x.
It SEC x because at the origin of it is exactly the same. Now we determine whether it has a vertical/horizontal stretch/shrink and translation shift.
Seeing it is a vertical stretch by 4 and translation 1 down.
I am not sure how to explain it in the more correct way. I have graphed it just to confirm if it is similar to your graph.