Question

US5NextUnit 4 - Pretest15Select the correct answer from each drop-down menu.A parabola is given by the equation y == -24%The equation of the directrix of the parabola isThe focus of the parabola isReset

Answer 1

Our parabola equation is (after playing with the equation a little)

`-(1)/(24)y^2\text{ = x}`

It is a horizontal parabola extending to the left side (because of the minus). Then, the focus (F) is a point (an ordered pair (a,b)) inside the area covered by the parabola (with this in mind is easy to answer the question, for the only point that satisfies this is (-6, 0)) that satisfies

`F\text{ = (}(1)/(4(-(1)/(24))),0\text{) = (-6, 0)}`

On the other side, after knowing the value of the focus, the directrix of this parabola must have the form

`x\text{ = -(-6) =6}`