H(t)=-16t+2t+5

Question

How long will it take to get to the ground

Answer 1

Assuming that the equation is a quadratic expressed as H(t) = -16t +2t + 5^2 and that H(t) is the height above the ground as a function of time (t), then the time required to hit the ground would be the time at which H(t) = 0.

 

Therefore, solve the following equation for t

 

-16t^2 +2t +5 = 0

 

Factoring the left side of the equation gives:

 

 (-8t+5) (2t +1) = 0

 

For this case set each of the factor terms equal to 0 and solve for t

 

-8t + 5 = 0                2t + 1 = 0

-8t = -5                      2t = -1

t = 5/8                       t = -1/2

 

The only real value for t is 5/8 because t=-1/2 cannot exist. Therefore, the answer is 5/8.