Monday, 2 September 2013

`y^2=-2x` 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=-2x`


Therefore,


`4p=-2`


Divide by 4 to obtain `p.`


`p=-2/4=-1/2`


Using the facts stated above we can simply write the equation of directrix and coordinates of focus.


Directrix is the line `x=1/2,` focus is the point `(-1/2,0)` and the axis of symmetry is `x`-axis.              ...

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=-2x`


Therefore,


`4p=-2`


Divide by 4 to obtain `p.`


`p=-2/4=-1/2`


Using the facts stated above we can simply write the equation of directrix and coordinates of focus.


Directrix is the line `x=1/2,` focus is the point `(-1/2,0)` and the axis of symmetry is `x`-axis.                                   

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