Which of the following parabolas opens down?

ANSWER

The correct answer is C.

EXPLANATION

The directrix of the parabolas are parallel to the x-axis. This means that, the orientation of the parabola is parallel to the y-axis. We compare the focus and the directrix to determine whether the parabola opens downwards or upwards.If the directrix is above the focus, then the parabola opens downwards.On the other hand if the directrix is below the focus , then the parabola must open upwards.If you look at option C, y=-2 isthe directrix. The focus is (3,-5). Since the the y-value of the focus , -5 is less than y=-2 which is the directrix, this parabola must open down.

The correct answer is C.

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