Differential Equations Help, non-linear first order with substitution

In summary, a differential equation is a mathematical equation used to model and solve real-world problems in various fields. There are two types of differential equations, linear and non-linear, determined by the appearance of the dependent variable and its derivatives. The order of a differential equation is the highest derivative that appears, with a first order equation involving only the first derivative. To solve a non-linear first order differential equation with substitution, you must first rearrange the equation and then substitute a suitable variable. Non-linear first order differential equations have many applications in fields such as population growth, chemical reactions, and mechanics. They are also used to model and analyze complex systems in physics, engineering, and biology.
  • #1
leomclaughlin
9
0
(r^2) (dT/dr)+B*r*T=T^2, with initial condition dT/dr |r=0 =0 where B is a constant


I've gotten it to this:

dT/dr = -BT/r + T2 / r2

by dividing everything by r2, then I substitute using λ= T/r which gives:


r * dλ/dr + lambda = -B * (λ) + λ^2


I don't know how to separate from here, any help is appreciated
 
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  • #2
Aren't you almost finished?

## r \frac{d\lambda}{dr} + \lambda = -B\lambda + \lambda^{2} \Rightarrow \frac{1}{-\lambda(B+1) + \lambda^{2}} \frac{d\lambda}{dr} = \frac{1}{r} ##
 

1. What is a differential equation?

A differential equation is a mathematical equation that describes the relationship between a function and its derivatives. It is used to model and solve many real-world problems in various fields such as physics, engineering, economics, and biology.

2. What is the difference between linear and non-linear differential equations?

A linear differential equation is one in which the dependent variable and its derivatives appear only in a linear way. This means that the highest power of the dependent variable or its derivatives is 1. On the other hand, a non-linear differential equation is one in which the dependent variable and its derivatives appear in a non-linear way, such as with powers of 2 or higher.

3. What is the first order in a differential equation?

The order of a differential equation is the highest derivative that appears in the equation. A first order differential equation involves only the first derivative of the dependent variable, while a second order equation involves the second derivative, and so on.

4. How do you solve a non-linear first order differential equation with substitution?

To solve a non-linear first order differential equation with substitution, you need to first rearrange the equation so that it is in the form of dy/dx = f(x,y). Then, you can substitute u = y/x (or any other appropriate substitution) to turn the equation into a separable one. Finally, you can integrate both sides and solve for y.

5. What are some applications of non-linear first order differential equations?

Non-linear first order differential equations have many applications in various fields, such as population growth and decay, chemical reactions, mechanics, and economics. They can also be used to model and analyze complex systems in physics, engineering, and biology.

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