SOLUTION: If a metal ball is thrown downward with an initial velocity of 22 feet per second (15 mph) from a 100 foot water tower, its height h in feet above the ground the ground after t sec

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Question 445294: If a metal ball is thrown downward with an initial velocity of 22 feet per second (15 mph) from a 100 foot water tower, its height h in feet above the ground the ground after t seconds is molded by h(t)=-16t^2-22t+100
determine symbolically when the height of the ball is 62 feet
Answer by lwsshak3(11628) About Me  (Show Source):
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f a metal ball is thrown downward with an initial velocity of 22 feet per second (15 mph) from a 100 foot water tower, its height h in feet above the ground the ground after t seconds is molded by h(t)=-16t^2-22t+100
determine symbolically when the height of the ball is 62 feet
..
h(t)=-16t^2-22t+100
62=-16t^2-22t+100
-16t^2-22t+38=0
-8t^2-11t+19=0
solve by following quadratic formula
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
..
a=-8, b=-11, c=19
t=[-(-11)+-sqrt(-11)^2-4*-8*19)]2*-8
t=[11+-sqrt(729)]/16=(11+-27)/-16
t=-16/-16=1
t=38/-16=-2.375 (reject, t=>0)
ans:
The height of the ball is 62 feet above the ground after 1 second.