Emergency Calculus Help Needed! Please!

Test Preparation AP Test Preparation
1

<p>So, my calculus teacher never has time to go over assigned problems or answer people's questions, I can't see him before or after school because of other obligations, and there are no students in my class I can ask for help (I'm usually the only one who knows what's going on). There's a quiz tomorrow based on the homework assignment from yesterday, and I really can't figure out what I'm doing wrong on a couple of the problems.</p>

<p>Please, can anyone help? I'm desperate.</p>

<ol>
<li>An object moving along a line has velocity v(t) = tcos(t) - ln(t+2), where 0 </= t </= 10. The object reaches maximum speed when t = ?</li>
</ol>

<p>The right answer is 9.538. But when I graph v(t), the maximum is at 6.419 (a wrong answer choice). I worked out and graphed v'(t) too, and sure enough at (9.538,0) the graph is going from negative to positive--a minimum. (6.419,0) is going from positive to negative. What am I missing here?</p>

<p>I'm going to take yet another crack at the other problem, and I'll post it too if I have to. Thank you SO MUCH for any help.</p>

2

<p>Maybe when they’re talking about maximum speed, not maximum velocity, it can be max speed going in the negative direction :)?</p>

3

<p>You’re given a specific interval to look at this velocity graph and the interval is 0 ≤ t ≤ 10. Speed is the absolute value of velocity to find the maximum speed you would look at each min/max to see which one is greater and that would be the greater speed. In this case the velocity might be negative it still has its maximum speed at t=9.538.</p>

4

<p>Thank you so much.</p>