Given a vetex (h,k) of a function parabola, the corresponding equation is:
[tex]f(x)=a(x-h)^2+k[/tex]
With (h,k)=(2,5) we get the equation:
[tex]f(x)=a(x-2)^2+5[/tex]
In order to find a, we use the given point (3,7) like this:
[tex]7=a(3-2)^2+5\\7=a+5\\a=7-5=2[/tex]
The equation is then:
[tex]f(x)=2(x-2)^2+5[/tex]