00:01
Hi there, so for this problem, we are told that p represents the number of grizzly birds in a population at times t years, when t is greater or equal than zero.
00:14
Now the population b is increasing at a rate derivative proportional to 600 minus b.
00:19
So that will be that the rate of change of the population with respect to time is a proportional, so there will be a constant of proportionality, then this time 600 minus b.
00:29
And then this, we're given also the initial population that is 400.
00:35
We need to find the population in terms of the time and the constant of proportionality gain.
00:40
Now what we need to do in this case is to separate the variables, okay? so let me just write this in the following way.
00:52
That will be 600 times the constant of proportionality minus the population times the constant of proportionality.
00:58
We can pass this term to the other side in here, so we will have this, then this is equal to 600 times the constant of proportionality.
01:10
Now we need to write a integrating factor that is related to this second term in here, so that will be the exponential of constant of proportionality times the time.
01:23
And we need to multiply everything by this.
01:25
So we can now write this, that this is the derivative with respect to time of the population times the exponential of the constant of proportionality times the time, then this is equal to 600 times k times the exponential of minus the constant of proportionality times the time.
01:48
Once we have this, we need to integrate both sides of this.
01:51
Well, we first need to separate the variables...