Question 1176570
<font face="Times New Roman" size="+2">


None of the answers given represent the focus of the given parabola.  A focus of a parabola is a point.  A parabola that is defined by an equation that contains two variables has a focus that is only correctly identified by an ordered pair.  The given answers are simply numbers.  Had you asked for the *[tex \Large y]-coordinate of the focus, you still would be out of luck because <i>that</i> answer isn't on the list either.


For a vertex form equation of a parabola with a vertical axis of symmetry, such as the one that you were given is:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ y\ =\ a(x\,-\,h)\,+\,k]


For this parabola, the vertex is at *[tex \Large (h,k)], the focus is at *[tex \Large \(h,k\,+\,\frac{1}{4a}\)], and the equation of the directrix is *[tex \Large y\ =\ k\ -\ \frac{1}{4a}].


You can do your own arithmetic to find the focus of your parabola.

																
John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
*[illustration darwinfish.jpg]

From <https://www.algebra.com/cgi-bin/upload-illustration.mpl> 
I > Ø
*[tex \Large \ \
*[tex \LARGE \ \ \ \ \ \ \ \ \ \  
								
{{n}\choose{r}}
</font>