First order linear differential equation

In summary, a first order linear differential equation involves a dependent variable, its derivative, and an independent variable, and can be solved using the method of integrating factors. It differs from a non-linear differential equation in that the solution is a straight line rather than a curve. These equations are used to model various real-world phenomena and initial conditions are crucial in determining a unique solution.
  • #1
physicsernaw
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Homework Statement



dy/dt = k*y*ln(y/M), where M and k are constants.

Show that y = Meaekt satisfies the above equation for any constant a.

Homework Equations



y' = ky
y = P0ekt

The Attempt at a Solution



Taking the derivative of y, I get:

(Meaekt)*(aekt)*k

which is,

ky*aekt

..and I'm stuck here.

EDIT:

Nevermind, I figured it out.

ln(y) = ln(M) + ae^(kt)

ae^(kt) = ln(y/M)

Plugging back in...

ky*ln(y/M)

:)
 
Last edited:
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  • #2
Well done! :)
 

1. What is a first order linear differential equation?

A first order linear differential equation is an equation that involves a dependent variable, its derivative, and an independent variable, with the derivative of the dependent variable appearing as a coefficient. It can be expressed in the form dy/dx + P(x)y = Q(x), where P(x) and Q(x) are functions of x.

2. How do you solve a first order linear differential equation?

To solve a first order linear differential equation, you can use the method of integrating factors. This involves multiplying both sides of the equation by an integrating factor, which is a function that helps to simplify the equation. Then, you can integrate both sides and solve for the dependent variable.

3. What is the difference between a linear and a non-linear differential equation?

A linear differential equation is one in which the dependent variable and its derivatives appear only as a linear combination, while a non-linear differential equation has terms that involve products or powers of the dependent variable and its derivatives. The solution to a linear differential equation is a straight line, while the solution to a non-linear differential equation is a curve.

4. How are first order linear differential equations used in real-world applications?

First order linear differential equations are used to model a wide range of physical phenomena, such as population growth, radioactive decay, and chemical reactions. They are also commonly used in engineering and economics to analyze systems and make predictions about their behavior.

5. What is the importance of initial conditions in solving a first order linear differential equation?

The initial conditions, also known as boundary conditions, are values of the dependent variable at a specific point. These conditions are necessary to uniquely determine the solution to a differential equation. Without them, there would be an infinite number of possible solutions to the equation.

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