Monday, June 17, 2019

-y^2=18x Graph the equation. Identify the focus, directrix, and axis of symmetry of the parabola.

Let y^2=4px be equation of parabola. Then equation of directrix is x=-p coordinates of focus are (p,0)  and axis of symmetry is x-axis.
In this case equation of parabola is
-y^2=18x
Multiply whole equation by -1.
y^2=-18x
Therefore,
4p=-18
p=-9/2
Directrix is line x=9/2 focus is point (-9/2,0) and axis pf symmetry is x-axis.   
https://en.wikipedia.org/wiki/Parabola

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