Notice that the given graph is a concave-up parabola.
Now, recall that the minimum value of a concave up parabola is the y entry of its vertex.
From the given graph we get that the vertex of the given parabola is:
[tex](0,-7)\text{.}[/tex]
The y entry of the above point is -7, then the minimum value of the given function is -7.
Answer: -7.
