SOLUTION: Find the equation of the directrix of the parabola (x+2)² = -16(y-3)

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Question 1023889: Find the equation of the directrix of the parabola (x+2)² = -16(y-3)
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
%28x%2B2%29%5E2+=+-16%28y-3%29.....
this is general form of your parabola:4p%28y-k%29+=+%28x-h%29%5E2
so, the vertex is at (-2, 3)
The coefficient of the unsquared part is -16, and this is also the value of 4p, so p+=+-4.
Since the x part is squared and p is negative, then this is a regular parabola that opens downward. This means that the directrix, being on the outside of the parabola, is four units above the vertex; so, the equation of the directrix of the parabola is y=4.
+graph%28+600%2C+600%2C+-15%2C+15%2C+-15%2C+15%2C+%281%2F-16%29%28x%2B2%29%5E2+%2B3%2C+4%29+