What do you need if you have to write the equation of a parabola?

This straight line outside the parabola is called the directrix. For parabolas that open either up or down, the standard form equation is (x - h)^2 = 4p(y - k). For parabolas that open sideways, the standard form equation is (y - k)^2 = 4p(x - h). The vertex or tip of our parabola is given by the point (h, k).

step-by-step explanation: