Question 1124571
More than one function possible.  Choosing vertical symmetry axis,


{{{y-6=a(x-4)^2}}}

{{{(y-6)/(x-4)^2=a}}}

{{{a=(-6)/(-2-4)^2}}}

{{{a=-6/6^2}}}

{{{a=-1/6}}}

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{{{y-6=-(1/6)(x-4)^2}}}

{{{highlight(y=-(1/6)(x-4)^2+6)}}}