How do I integrate dy/dt=ay-b in differential equations?

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In summary, the conversation is about solving a differential equation with the form dy/dt=ay-b. The book suggests factoring out the a and dividing both sides by (y-b/a), resulting in (dy/dt)/(y-b/a)=a. However, the next step of integrating both sides is unclear, and the person gets stuck. After some confusion, they realize their mistake and the correct solution is ln | y – (b/a) | = at + c.
  • #1
agent_509
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I am just getting started on learning differential equations, and I'm stuck on this one:

dy/dt=ay-b​

the book tells me to factor out the a, and then divide

dy/dt=a(y-b/a)

(dy/dt)/(y-b/a)=a​

This is where I get stuck, it completely skips over what to do next and just says to integrate both sides, and you come up with this

ln | y – (b/a) | = at + c
I multiplied both sides by dt to get

[1/(y-b/a)]dy=a dt​

but I don't see how integrating both sides gets the above equation, I instead get

ln(ay-b)=at+c​


what am I doing wrong?
 
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  • #2
never mind, I'm an idiot, thanks
 

FAQ: How do I integrate dy/dt=ay-b in differential equations?

How do I find the general solution for dy/dt=ay-b?

The general solution for this differential equation is y = (b/a) + Ce^(at), where C is a constant.

Can you explain the meaning of each variable in the differential equation dy/dt=ay-b?

The variable "y" represents the dependent variable, while "t" is the independent variable. The coefficient "a" represents the rate of change of y with respect to t, and "b" is a constant term.

How do I find the particular solution for dy/dt=ay-b if initial conditions are given?

To find the particular solution, substitute the initial conditions for y and t into the general solution y = (b/a) + Ce^(at). This will give you an equation with only one unknown, C. Solve for C and substitute it back into the general solution to get the particular solution.

Can you provide an example of a real-world application of dy/dt=ay-b?

This differential equation can be used to model exponential growth or decay in various fields such as population growth, radioactive decay, and economic growth.

How can I solve dy/dt=ay-b numerically using a computer program?

There are various numerical methods that can be used to solve this differential equation, such as Euler's method or the Runge-Kutta method. These methods involve breaking the differential equation into smaller steps and using iterative calculations to approximate the solution. There are many computer programs and software packages available that can perform these calculations for you.

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