Question 1176630
Are you asking for equation of parabola like that?



{{{y=a(x-h)^2+k}}}
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Vertex is at  (h,k), and the value of "a" is found when you substitute for the given point in your example,  of  (2,6).




But there is the other simple form in case axis of symmetry parallel to horizontal axis.
{{{x=a(y-k)^2+h}}}