SOLUTION: A person standing close to the edge on the top of a 160-foot building throws a baseball vertically upward. The quadratic function, s(t)= -16t^2+64t+160 models the ball’s height w

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: A person standing close to the edge on the top of a 160-foot building throws a baseball vertically upward. The quadratic function, s(t)= -16t^2+64t+160 models the ball’s height w      Log On


   



Question 1146035: A person standing close to the edge on the top of a 160-foot building throws a baseball vertically upward. The quadratic function, s(t)= -16t^2+64t+160 models the ball’s height where s(t) is the height and t is the number of seconds after the ball is thrown.
(Note that s(t) is just function notation for the height of the ball and NOT s
multiplied by t; also note where the initial height and initial velocity values play a role in the equation.)
After how many seconds is the ball 100 feet above the ground’s surface? Round answer to the nearest hundredth. Don’t forget units!!

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
There should be just one solution since the person
Is already 160 above ground
+s%28t%29+=+-16t%5E2+%2B+64t+%2B+160+
+s%28t%29+=+100+
+100+=+-16t%5E2+%2B+64t+%2B+160+
+-16t%5E2+%2B+64t+%2B+60+=+0+
+-4t%5E2+%2B+16t+%2B+15+=+0+
Use quadratic formula to solve for t
( use the positive solution ).