Respuesta :
Answer:
t = 4
Step-by-step explanation:
Given that:
[tex]h(t) = 17t^2 + 68t + 80[/tex]
When h(t) = 80, we have that:
[tex]80 = -17t^2 + 68t + 80\\\\=> 0 = -17t^2 + 68t\\\\=> 17t^2 - 68t= 0\\\\=> 17t(t - 4) = 0\\\\=> t = 0, t = 4\\\\[/tex]
t = 0 represents when the ball has not been thrown at all, in its initial position.
t = 4 represents the time taken for the ball to hit the roof of the building on its way down.
Hence, our answer is t = 4. (t is in secs)
Answer:
t = 4 seconds.
it takes the ball 4 seconds to hit the roof of the building on its way down
A ball is thrown straight up from the roof of an 80-foot building and it's height is modeled by the h(t) = -17t^2 + 68t + 80, where h is the height in feet and t is time in seconds. How long (in sec) will it take the ball to hit the roof of the building on its way down? That is, solve h(t) = 80. (Enter an exact number.)
Step-by-step explanation:
Given that;
h(t) = -17t^2 + 68t + 80
At h(t) = 80
-17t^2 + 68t + 80 = 80
-17t^2 + 68t = 80 - 80
-17t^2 + 68t = 0
-17t(t-4) = 0
So,
-17t = 0 or. t-4 = 0
t = 0 or. t = 4
Since t cannot be zero, since t = 0 is the time the ball was thrown up.
t = 4 seconds.
it take the ball 4 seconds to hit the roof of the building on its way down
