00:01
For this problem, we are told that the number of smartphone users and penetration in the united states continues to grow steadily.
00:08
The number of users in millions from 2011 through 2015 is projected to grow at the rate of r of t equals 14 .3 for t between 0 and 4 million per year.
00:17
The number of users in 2011, or t equals 0, was 90 .1 million.
00:23
We're then asked to find an expression giving the projected number of smartphone users in year t, and what is the estimated number of smart phone users in year t? phone users in 2015.
00:33
So what we want to do here is take the anti -derivative.
00:37
I'm not sure if you've seen this notation by this point in the book, but this is the notation for anti -derivative or integral.
00:43
We want to, first of all, take the anti -derivative of r of t.
00:48
So the anti -derivative r of t is just going to be the anti -derivative of 14 .3, which is going to be 14 .3t plus a constant.
00:57
Now we need to determine that constant...