A model rocket is launched. The height, in feet, of the rocket h(t) at t (t>=0) seconds after launch is determined by the equation h(t)= (-1/2t)^2 + 15t. The maximum height of the rocket is 112.5 feet.
(a) Find the number of seconds after launch it takes for the rocket to reach its maximum height. [Show all work]
(b) For how many seconds will the rocket be at a height of more than 100 ft? [Show all work]
ok so its not like i tried it, i did, and let me show what i did.
first i plugged 112.5 for h(t) and got an answer of t=15 for part a.
for part b i plugged in 100 for h(t) and got 10 and 20. but i rejected 20 because thats higher than 15 which is the amount of time to reach the maximum height so that makes no sense. so i did 15 - 10 and got 5 for part b.
am i correct?