Question 174663
Hello.  I received your e-mail.  You need more help, right?
 
Here is one of your questions:
 
 

5) Crossing a wooden bridge at Letchworth Park, Melissa drops a penny into the water below for good luck. If the height of the penny is modeled by the function h(t)=64 - 16t^2, where t represents time in seconds and h(t) is height in feet, how many seconds did it take the penny to hit the water?
(a) 1 (b) 2 (c) 3 (d) 4

 

Let h(t) = 0 


0 = 64 - 16t^2 


Subtract 64 from both sides.
 
-64 = -16t^2
 
Now divide both sides by -16.
 
-64/-16 = t^2
 
64/16 = t^2
 
4 = t^2
 
Finally take the square root of both sides of the equation.
 
sqrt{4} = sqrt{t^2}
 
2 = t
 
The answer is choice (b).
 
Do you need help with the trig equation question?
 
Happy new year!