Give the focus, directrix, and axis for the parabola.
-A projectile is thrown upward so that its distance above the ground after $\mathrm { t }$ seconds is $\mathrm { h } = - 15 \mathrm { t } ^ { 2 } + 480 \mathrm { t }$. What is its maximum height?
A) $3840 \mathrm { ft }$
B) $5760 \mathrm { ft }$
C) $2880 \mathrm { ft }$
D) $1920 \mathrm { ft }$

Question

Quizplus · Accepted Answer

The maximum height is found at the vertex of the parabola represented by the equation $h = -15t^2 + 480t$. The vertex formula $t = -\frac{b}{2a}$ gives $t = -\frac{480}{2(-15)} = 16$. Plugging $t = 16$ back into the equation gives the maximum height $h = -15(16)^2 + 480(16) = 3840 \, \text{ft}$.

Give the Focus, Directrix, and Axis for the Parabola t\mathrm { t }t

Give the Focus, Directrix, and Axis for the Parabola $\mathrm { t }$