Modeling Population Growth: Solving for P(t) Using Integration

gtfitzpatrick
Messages
372
Reaction score
0

Homework Statement


a population P(t) is modeled by the equation dP/dt = 0.0004P(P-150), Find a formula which gives the population, P(t), at a general time t.

Homework Equations





The Attempt at a Solution



swapping over

dt=1/0.004P(P-150) dP
then i integrate both sides

dt becomes t+c but I'm i'm not sure how to integrate the the dP side, any pointers please?
 
Physics news on Phys.org
Are you able to integrate \int\frac{dx}{x}?
 
First, 1/0.004= 250. You have
250\int\frac{dP}{P(P-250)}dP

Use "partial fractions". Write
\frac{1}{P(P-250)}= \frac{A}{P}+ \frac{B}{P- 250}
Find A and B and do it as two separate integrals.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top