If a rock falls from a height of 33 meters on Earth, the height H (in meters) after x seconds is approximately H(x)=33-4.9x^2. When is the height of the rock 10 meters?
(a) What is the height of the rock when x = 1.8 seconds?
(b) When is the height of the rock 10 meters?
(c) When does the rock strike the ground?

I was able to get the answers for the first 2 questions. (a) is 17.124 and (b) 2.17. It's (c) that I'm still having trouble with.

Question

If a rock falls from a height of 33 meters on Earth, the height H (in meters) after x seconds is approximately H(x)=33-4.9x^2. When is the height of the rock 10 meters?
(a) What is the height of the rock when x = 1.8 seconds?
(b) When is the height of the rock 10 meters?
(c) When does the rock strike the ground?

I was able to get the answers for the first 2 questions. (a) is 17.124 and (b) 2.17. It's (c) that I'm still having trouble with.

anonymous · Answer

sorry that was not right set 4.9x^2=33 and solve for x

anonymous · Answer

Here's what I did:
$$4.9x^2=33$$
$$\frac{ 4.9x^2 }{4.9} = \frac{ 33 }{ 4.9 }$$
$$\sqrt{x^2} = \sqrt{6.73}$$
x = 2.59

I'm doing this homework on mymathlab and it says that my answer was wrong. I don't get what I did wrong.

anonymous · Answer

try 2.6

anonymous · Answer

because if you dont round the full answer comes out to 2.59513

anonymous · Answer

Oh, 2.6 worked. Thanks for the help!

anonymous · Answer

no problem