Answer:
[0, 7]
Step-by-step explanation:
We want the height to be greater than or equal to 32 ft, so ...
704 +16t -16t^2 ≥ 32
t^2 -t -42 ≤ 0 . . . . . . . . . . . subtract 32, divide by -16
(t -7)(t +6) ≤ 0
This inequality will be true for values of t between -6 and +7. Since we're only concerned with times t ≥ 0, the appropriate solution interval is ...
0 ≤ t ≤ 7 . . . . [0, 7] in interval notation
