Concept explainers
To find: The vertex, focus and directrix of the parabola x+y2=0 and verify with the help of graphing utility.

Answer to Problem 60E
The vertex, focus and directrix of the parabola x+y2=0 are (0,0) , (−14,0) , x=14 respectively. The graph of the parabola with vertex, focus and directrix is shown in Figure (1).
Explanation of Solution
Given information:
The equation of the parabola is x+y2=0 .
Calculation:
Simplify the equation of the parabola.
x+y2=0y2=−x
Compare the given equation of parabola with general horizontal axis parabola equation (y−k)2=4p(x−h) . This gives the value of h , k , p as 0 , 0 , −14 respectively.
The vertex of the parabola x+y2=0 is (h,k)=(0,0) .
The focus of the horizontal axis parabola x+y2=0 is:
(h+p,k)=(0+(−14),0)=(−14,0)
The directrix of the parabola x+y2=0 is:
x=h−p=0−(−14)=14
Therefore, the vertex, focus and directrix of the parabola x+y2=0 are (0,0) , (−14,0) , x=14 respectively.
The graph of the parabola x+y2=0 with vertex, focus and directrix is shown below.
Figure (1)
Here we can verify the vertex, focus, directrix of the parabola x+y2=0 are (0,0) , (−14,0) , x=14 respectively.
Chapter 9 Solutions
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