The standard form of a quadratic equation is:
[tex]y=a(x-h)^2+k[/tex]
in this equation the vertex is (h,k). Moreover, if a>0 the parabola opens upward and vertex is a reletive minimum; if a<0 the parabola opens downward and the vertex is a maximum.
In this case the vertex is (-2,-1) and since a=1/3 then this is a minimum of the parabola.
