Seperable Differential equation

In summary, the equation dm/ds=m can be solved using the technique of separation of variables. The solution is given by m(s)=7e^(k-1), where k is a constant determined by the initial condition m(1)=7.
  • #1
nick.martinez
51
0
dm/ds=m ; m(1)=7

when i find the diff eq

∫dm/m=∫ds

ln|m|+c1=s+c2 ; k=c2-c1

ln|m|=s+k
e ^ both sides

m(s)=e^(s+k) ; m(1)=7

m(1)=e^(1)*e^(k)=7
i am stuck here. not sure how to proceed please help.
 
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  • #2
What are you trying to figure out with your initial condition?

Can you solve this equation using another technique?
 
  • #3
nick.martinez said:
dm/ds=m ; m(1)=7

when i find the diff eq

∫dm/m=∫ds

ln|m|+c1=s+c2 ; k=c2-c1
There is really no need to write both c1 and c2. It's perfectly proper to immediately combine the two "constants of integration" to write ln|m|= s+ k.

ln|m|=s+k
e ^ both sides

m(s)=e^(s+k) ; m(1)=7

m(1)=e^(1)*e^(k)=7
i am stuck here. not sure how to proceed please help.[/QUOTE]
So e^k= 7e^{-1}.

e^(s+k)= e^k e^s so m(s)= 7e^{-1}e^k or m(s)= 7e^(k-1).
 

FAQ: Seperable Differential equation

What is a separable differential equation?

A separable differential equation is an equation that can be written in the form dy/dx = f(x)g(y), where f(x) and g(y) are functions of x and y, respectively. This means that the dependent variable and independent variable can be separated on opposite sides of the equation.

How do you solve a separable differential equation?

To solve a separable differential equation, you must start by separating the variables on opposite sides of the equation. Then, integrate both sides with respect to their respective variables. This will result in a general solution, which can be further simplified by using any initial conditions given in the problem.

What are the applications of separable differential equations?

Separable differential equations are commonly used in physics, engineering, and other scientific fields to model various physical phenomena. They can be used to describe the rate of change of a quantity over time, such as the growth of a population or the decay of a radioactive substance.

Can all differential equations be solved using separation of variables?

No, not all differential equations can be solved using separation of variables. This method only works for equations that are in the form dy/dx = f(x)g(y). Other methods, such as substitution or variation of parameters, may be necessary to solve other types of differential equations.

Are there any limitations to using separation of variables to solve differential equations?

One limitation of using separation of variables is that it can only be applied to first-order differential equations. Additionally, it may not always be possible to find a closed-form solution using this method, especially for more complex equations. In these cases, numerical methods may be used to approximate the solution.

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