SOLUTION: A rocket is fired from the floor of the grand canyon. The height of the rocket, h(t) in metres above the floor of the canyon after t seconds is modeled by the function h(t)= -5t^
Question 1127987: A rocket is fired from the floor of the grand canyon. The height of the rocket, h(t) in metres above the floor of the canyon after t seconds is modeled by the function h(t)= -5t^2+240t. A person sitting at the top of the canyon, 1734m above its floor, can only see the rocket when it is above that height. FOr how many seconds will the rocket be visible?
Thank you Answer by ikleyn(52778) (Show Source):
You need to solve the equation
h(t) = 1734, which is the same as -5t^2 + 240t = 1734, or, equivalently,
5t^2 - 240t + 1734 = 0.
Find its roots that represent the time moments when the "rocket" is at this level;
then take the difference of the roots.
