The function y = –16t^2 + 224 models the height y in feet of a stone t seconds after it is dropped from the edge of a vertical cliff. How long will it take the stone to hit the ground? Round to the nearest hundredth of a second.
0.25 seconds
5.29 seconds
7.48 seconds
3.74 seconds

Question

The function y = –16t^2 + 224  models the height y in feet of a stone t seconds after it is dropped from the edge of a vertical cliff. How long will it take the stone to hit the ground? Round to the nearest hundredth of a second. 
0.25 seconds
5.29 seconds
7.48 seconds
3.74 seconds

anonymous · Answer

@e.cociuba

e.cociuba · Answer

If y is the height of the stone when it hits the ground, then what does y equal?

e.cociuba · Answer

So... Wat do u think??

anonymous · Answer

Im confused on how to solve -16t^2+224. Can you explain to me how to do it so that I can do it on the next problem lol I think I need to start there

anonymous · Answer

So it should look like 0=-16t^2 +, wait how'd you get 486?

e.cociuba · Answer

Oops I mean: 
Set y to zero and solve for t:
 y = -16t^2 + 224 MY bad...

e.cociuba · Answer

Then u do:  
0 = -16t^2 + 224
 16t^2 = 224 
Can u solve from here?...

anonymous · Answer

would you divde 224 but -16?

e.cociuba · Answer

Not by -16.. 
1) add 16t^2 to both sides
2) divide by 16
3) And then take the square root

anonymous · Answer

so then its 0=-16t^2 +224+ -16t^2/ 16

e.cociuba · Answer

0 = -16t^2 + 224
 16t^2 = 224  
1.) You divide by 16 on each side. So it would be 224/16= 14 
2.) Then u take the square root of 14 
3.) Then answer I got was 3.74165 (round and u get D. (3.74 seconds))

e.cociuba · Answer

Does tht make sence??...

anonymous · Answer

Oh yes it does I see what I was doing wrong. I just put too many -16t^2's! Thank you so much!! :))

e.cociuba · Answer

Haha Np:)