the height in feet of a diver above the surface of a pool is given by the equation h(t)=-16t^2+12t+8, where t is the time in seconds after the diver jumps.

Question

How many seconds after jumping is the divers height 5 meters? How long does it take the driver to reach the water?

 

Answer 1

You are given

 

h(t) = -16t² + 12t + 8 

 

This equation gives the diver's height in feet above the water, with time t in seconds.  If you want to know how many seconds it takes to reach 5 meters, convert 5 meters to feet, and set the number equal to h(t), and simplify.  You will end up with a quadratic equation in t.  Solve for t.  (Note: If there is no real solution for t, then the diver never reaches 5 meters.)  

 

To find out when the diver reaches the water, set the height equal to zero.  You will have

 

-16t² + 12t + 8 = 0

 

Solve this quadratic equation for t.