00:01
For this problem, we can just plug in some specific values into s, the function s of t, and we can compute the second order derivative for s with respect to t.
00:11
So this is the second derivative.
00:13
And since we want to find the inflection point, and be careful, our domain will be t greater than zero.
00:27
We only consider this as our domain.
00:30
So we set the second derivative equals to zero.
00:33
That means this quadratic equation equals to 0.
00:41
So we can use calculators to get two results.
00:46
T equals to 28 .57 and t equals to 85 .71.
00:56
So we have three intervals from 0 to 28 .57.
01:03
The second derivative of t, is positive, so it's concave upward...