look at this graph: what is the maximum value of this function?

Explanation:

Step1: Observe the graph

The graph is a parabola opening downwards. The maximum - value of a downward - opening parabola is at its vertex.

Step2: Locate the vertex

By looking at the graph, the vertex of the parabola is at the point where the function reaches its highest value. The y - coordinate of the vertex gives the maximum value of the function. The vertex appears to be at approximately (2, 4).

Answer:

4