solving quadratic equations

[fairss]

A model rocket is shot into the air and its path is approximated by h=-5t^2+30t, where h is the height of the rocket above the ground in metres and t is the elapsed time in seconds.
a) when will the rocket hit the ground?
b) what is the maximum height of the rocket?

[theshadow]

A model rocket is shot into the air and its path is approximated by h=-5t^2+30t, where h is the height of the rocket above the ground in metres and t is the elapsed time in seconds.
a) when will the rocket hit the ground?
b) what is the maximum height of the rocket?

They show you how to do these in this lesson.

For a), plug in the "height above ground" for "when it's touching the ground" and then solve for t.
For b), find the vertex. The first number is the time at the max and the second number is the height at the max.

Please write back if you get stuck.