A parabola can be expressed in vertex form as follows
[tex]y=a(x-h)^2+k[/tex]
Where (h,k) is the vertex of the parabola, and a is the coefficient, if a is negative, it means the parabola is opening downside (like this case).
According to the given graph, the vertex is at (2,4), which means h=2 and k=4. Also, a is negative since the parabola is towards the downside.
Therefore, the equation is
[tex]y=-(x-2)^2+4[/tex]
