Answer:

Now we can set up the derivate equal to 0 and we have:

And solving for t we got:

For the second derivate respect the time we got:

So then we can conclude that t = 4.206 is a maximum for the function.
And the corresponding height would be:

So the maximum occurs at t = 4.206 s and with a height of 135.468 m
Step-by-step explanation:
For this case we have the following function:

In order to maximize this function we need to take the first derivate respect the time and we have:

Now we can set up the derivate equal to 0 and we have:

And solving for t we got:

For the second derivate respect the time we got:

So then we can conclude that t = 4.206 is a maximum for the function.
And the corresponding height would be:

So the maximum occurs at t = 4.206 s and with a height of 135.468 m