What kind of differential equation is this

  • #1

Main Question or Discussion Point

I am trying to solve a real-world problem, and I have modeled it with the following equation:
[tex]\frac{dS}{dt}-3\left (\frac{150-S}{100-t} \right )+\frac{2S}{100+t}=0[/tex]

What kind of differential equation is that? Is it solvable analytically ?
Maple tells me it is linear, but I don't see how...
 
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Answers and Replies

  • #2
lurflurf
Homework Helper
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126
I forget what that is called, but it is linear and easily solved. Clear denominators
(t-100)(t+100)s'(t) = (t+500) s(t)-450 t-45000
solve
(t-100)(t+100) s'(t) = (t+500) s(t)
use that to solve the original
naturally terms like
(t-100)m(t+100)n
arise
 
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  • #3
798
34
I am trying to solve a real-world problem, and I have modeled it with the following equation:
[tex]\frac{dS}{dt}-3\left (\frac{150-S}{100-t} \right )+\frac{2S}{100+t}=0[/tex]

What kind of differential equation is that? Is it solvable analytically ?
Maple tells me it is linear, but I don't see how...
It is a first order linear ODE
Of course it is easy to solve it, thanks to classical method.
"Linear" means linear relatively to the sought function S (There is no S² nor other functions of S. There are only S and S' in the equation).
It doesn't mean linear relatively to the variable t.
 
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  • #4
108
2
Write: dS/dt + f(t)S = g(t).
 
  • #5
81
1
I am trying to solve a real-world problem, and I have modeled it with the following equation:
[tex]\frac{dS}{dt}-3\left (\frac{150-S}{100-t} \right )+\frac{2S}{100+t}=0[/tex]

What kind of differential equation is that? Is it solvable analytically ?
Maple tells me it is linear, but I don't see how...
Looks like rate of equation that determines solution or volume of liquid into a tank and out. Again it is solvable via separable equations.
 

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