SOLUTION: A ball is thrown downward from a window in a tall building. Its position at time t in seconds is s=16t^2+32t, where s is in feet. How long (to the nearest tenth) will it take the

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: A ball is thrown downward from a window in a tall building. Its position at time t in seconds is s=16t^2+32t, where s is in feet. How long (to the nearest tenth) will it take the      Log On

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Question 116934: A ball is thrown downward from a window in a tall building. Its position at time t in seconds is s=16t^2+32t, where s is in feet. How long (to the nearest tenth) will it take the ball to fall 149 feet?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
s+=+16t%5E2+%2B+32t
s+=+149ft
149+=+16t%5E2+%2B+32t
16t%5E2+%2B+32t+-+149+=+0
Use the quadratic formula
t+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
when equation is in the form
ax%5E2+%2B+bx+%2B+c+=+0
a+=+16
b+=+32
c+=+-149
t+=+%28-32+%2B-+sqrt%28+32%5E2-4%2A16%2A%28-149%29+%29%29%2F%282%2A16%29+
t+=+%28-32+%2B-+sqrt%2810560%29%29%2F32+
t+=+%28-32+%2B-+102.762%29%2F32+
t+=+-1+%2B-+3.2
t+=+2.2sec answer
t+=+-+4.2 reject this solution
It will take the ball 2.2 sec to fall 149 ft