Question

Suppose you throw a ball up in the air from the top of a 160 foot building. It's height h in feet after t seconds is given by the function h= -8t^ + 48t + 160

a) When does the ball reach it's maximum height?

b) What is the ball's maximum height?

c) How long does it take before the ball comes back and hits the ground?

d) How high will the ball be at 2 seconds?

I know it's a quadratic equation but not sure how to set it up to find solutions by factoring or a parabola.

Answer 1

Ignoring the fact that this equation would violate the laws of gravity on earth ....

find the vertex in the form (t,h)
the value of t is your a) answer, and the value of h is your b) answer.
Use the method that was taught to you.

c) set -8t^2 + 48t + 160 = 0
divide by -8
t^2 - 3t - 20 = 0
solve using the quadratic equation, of course you would use only the positive value of t.

d) sub in t = 2 into your equation.

Answer 2

If I divide the quadratic equation by a -8 wouldn't it be
t^ - 6t - 20 = 0

Answer 3

t^2 - 6t - 20 = 0

Answer 4

yes, you are right, my mental error or senior moment.

Answer 5

and that can't be factored