Question 63909
Mark launched a model rocket with an initial speed of 180 ft per second. After how many seconds will Mark's rocket reach a height of 464 ft?
a) The formula h=rt-16t^2 gives the height of an object projected upward at a rate of r feet per second after t seconds...NO IT IS WRONG ..R IS THE INITIAL VELOCITY AND NOT VELOCITY AT TIME T.. Rewrite this equation substituting the data you are given. 
AT T=0,U=INITIAL SPEED = 180 FPS = R...AT H=464...T=?...SUBSTITUTING
464=180T-16T^2
4T^2-45T+116=0
4T^2-16T-29T+116=0
4T(T-4)-29(T-4)=0
(T-4)(4T-29)=0
T=4....OR......29/4
THAT IS 4 SECS AFTER START ON ITS UPWARD JOURNEY
AND 29/4 SECS AFTER START ON ITS DOWNWARD JOURNEY.

b) Solve the equation and answer the problem. 
c) After how many seconds will it be at that height again?
THANK YOU!!!!!!