Question 1168614
A quick sketch and simple computation shows that directrix is x=7, or all points in the plane, (7,y).


Distance from (x,y) to (-3,4) is equal to distance from (x,y) to (7,y).


Setup using the Distance Formula definition for parabola and start with
{{{(x+3)^2+(y-4)^2=(x-7)^2+(y-y)^2}}}


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Upon doing the algebra steps an equation found {{{highlight((y-4)^2=-20(x-2))}}}.