# Which one is a Logistic Differential Equation?

Which of the following DE is not logistic?

$\displaystyle\text{a. }P'=P-P^{2}\\\displaystyle\text{b. }\frac{dx}{dt}=0.8x-0.004x^2\\\displaystyle\text{c. }\frac{dy}{dx}=0.01y\left(100-y\right)\\\displaystyle\text{d. }\frac{dR}{dt}=0.16\left(350-R\right)$

The answer btw is letter d.

I don't quite know yet what's a logistic function but Here i found from

http://en.wikipedia.org/wiki/Logistic_function

$\frac{d}{dt}P(t)=P(t)\left(1-P(t)\right)$

From the looks of letter a,b and c, it may be done by a partial fraction equation which makes it a natural logarithm and using e for the finale, but i don't see how this makes a logistic DE. And from letter d i seem to get $\ln\left(350-R\right)=e^{0.16t}+C$,and i don't know how this is not logistic

EDIT: hey i just realize that d is the answer because it has no R parameter at the 0.16 part. How stupid of me

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Either write a good descriptive answer and accept it. Or, alternatively, delete this post. –  user45099 Apr 5 '13 at 18:25