Step-by-step explanation:
Since we are given the vertex, it would be wise if we put it in vertex form.
[tex]y = a(x - h) {}^{2} + k[/tex]
where (h,k) is the vertex
Here we know (h,k) is the (3,6), aand (x,y) is (4,4) so, solving for a.
[tex]4 = a(4 -3 ) {}^{2} + 6[/tex]
[tex]4 = a + 6[/tex]
[tex]a = - 2[/tex]
So our equation is
[tex]y = - 2(x - 3) {}^{2} + 6[/tex]