A parabola, with its vertex at (0,0), has a focus on the negative part of the y-axis. Which statements about the parabola are tr
ue?
Check all that apply.
The directrix will cross through the positive part of the y-axis.
The equation of the parabola will be in the form y2 = 4px where the value of p is negative.
The equation of the parabola will be in the form x2 = 4py where the value of p is positive.
The equation of the parabola could be y2 = 4x.
The equation of the parabola could be x2 = y.
Check all that apply.
The directrix will cross through the positive part of the y-axis.
The equation of the parabola will be in the form y2 = 4px where the value of p is negative.
The equation of the parabola will be in the form x2 = 4py where the value of p is positive.
The equation of the parabola could be y2 = 4x.
The equation of the parabola could be x2 = y.
2 answers:
In the attached diagram you can see all four possible placement of a parabola with vertex at origin.
You know that parabola has a focus on the negative part of the y-axis. Then you chould consider the 4th placement of parabola.
As you can see the directrix crosses through the positive part of the y-axis. (Option A is true).
The equation of parabola is , where a is a positive number, then all four remaining options are false, because each of these options gives you wrong equation of parabola.
Answer: correct choice is A.
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