Use the formula h=-16t^2+80x+200

Question

What is the maximum height the rocket reached?

How long will it take to reach maximum height?

Answer 1

I assume you meant to say

h(t) = -16t² + 80t + 200

(Note your second term should be 80t, not 80x.)

Maximum h is at the vertex of the h-vs.-t parabola, which is at

t = -80 / [2(-16)] = ?

Evaluate h(t) at this value of t to get maximum h.