identify the vertex,focus,and directrix of the equation
y^2-4x-2y=3
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identify the vertex,focus,and directrix of the equation
y^2-4x-2y=3
This web site tells a lot about parabolas:Quote:
identify the vertex,focus,and directrix of the equation
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Parabola - Wikipedia, the free encyclopedia
(First equation)
- axis parallel to the y-axis
- vertex: (h,k)
- focus: (h,k+p)
- directrix: y=k-p
or
(Second equation)
- axis parallel to the x-axis
- vertex: (h,k)
- focus: (h,k+p)
- directrix: y=k-p
Your equation is
The x's are now on the right, the y's on the left side. Let's concentrate on the left side. That's the most difficult since we have a square term. We note that
but we need a 1 on that side also. Add a 1 to both sides.
Now factor
That looks like the second equation with k=1, p=1, h=-1.
You should be able to figure out the question now.
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