Write an equation for the parabola who’s vertex is at (3,6) and which passes through (4,4)

Problem
Solution
For this case we know that the vertex is given by (3,6) and the genera equation for a parabola is given by:
y= a(x-h)^2 +k
Where h = 3, k=6 and replacing we have:
y= a(x-3)^2 +6
And we can find the value of a with the point given x= 4, y=4
4= a(4-3)^2 +6
4= a +6
a= 4-6=-2
And the correct equation would be:
d. y= -2(x-3)^2 +6