Question

How do I find the function of this graph?

Answer 1

where's the graph?

Answer 2

@Cardinal_Carlo

Answer 3

I see that this is the graph of a parabola, and that quite a lot of info can be derived directly from the graph:
1. vertex
2. two horizontal intercepts
3. the vertical intercept

Take a look at the graph and then try to identify these several items (vertex, intercepts, etc.)