# A ball is thrown straight up from the top of a 80 foot tall building with an initial speed of 64 feet per second. The height of the ball as a function of time can be modeled by the function h(t)=-16t^2+64t+80. When will the ball be 144 feet above ground?

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When will the ball hit the ground?

When will the ball hit the ground?

##### 1 Answer

Oct 26, 2017

after

#### Explanation:

factorise:

in this example,

- solving for
#t# using the quadratic equation:

assuming the time is in seconds, it will take

- solving graphically:

red:

blue:

to find where

[

this means that after