Solve 1st-Order DE: Riccati Equation Homework

  • Thread starter astrofunk21
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In summary, the problem requires finding general solutions for a 1st-order differential equation and the student has attempted to solve it using a particular solution approach. They have assumed y1 = A/x and found the derivative to be -A/x^2. By substituting this into the original equation, they have obtained a quadratic equation and used the quadratic formula to find two possible solutions for A. However, they are unsure if these solutions are correct and are seeking guidance.
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astrofunk21
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Homework Statement


Find the general solutions of the following 1st-order DE: y' = by2+(1/4bx2) where b ≠ 0 is a constant.

Homework Equations


Now this is a Riccati Equation, I know that. In my math class we've only learned to solve DEs the following ways:
a. Separation of Variables
b. Substitution
i. Polynomial Substitution
ii. Homogeneous Substitution
iii. Bernoulli DE

The Attempt at a Solution


The first thing I did was to assume a particular solution, which I made y1 = A/x With this I found the derivative of it: y' = -A/x2 and then y2 = A2/x2

Using these I subbed them into the original equation giving me:
-A/x2 = bA2/x2 + 1/4bx2

After this I solved to make it equal to zero which is:
0 = A + bA2 + 1/4b

From this I used the quadratic formula to get:
A = 0 and A = -1/b

After this I don't know where to go, I don't know if those are even right. Could anyone give me some direction and at the same time check if what I have so far is right?

Thanks in advance
 
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  • #2
Anything?
 
  • #3
Is it that hard? Haha
 

1. What is a 1st-order differential equation?

A 1st-order differential equation is an equation that involves a function and its first derivative. It is written in the form dy/dx = f(x,y), where y is the dependent variable and x is the independent variable. Solving 1st-order differential equations involves finding a function that satisfies the equation.

2. What is a Riccati equation?

A Riccati equation is a type of 1st-order differential equation that has the form dy/dx = f(x,y) = a0 + a1y + a2y^2, where a0, a1, and a2 are constants. These equations are commonly used in physics and engineering to model nonlinear behavior.

3. How do you solve a Riccati equation?

The general solution to a Riccati equation can be found using the substitution method. By substituting y = u + 1/v into the equation, it can be transformed into a linear equation in terms of u. This can then be solved using standard methods for 1st-order linear equations. Once u is found, the solution for y can be obtained by solving for v.

4. Are there any special cases in solving Riccati equations?

Yes, there are two special cases in solving Riccati equations. The first is when the equation is homogeneous, meaning that the constant term a0 is equal to 0. In this case, the substitution method is not necessary and the equation can be solved using standard methods for 1st-order equations. The second special case is when the equation is of the form dy/dx = f(x,y) = -a1y + a2y^2, where a1 and a2 are constants. This type of equation can be solved using the substitution y = 1/v.

5. What are some applications of Riccati equations?

Riccati equations have various applications in physics, engineering, and economics. They are commonly used to model nonlinear systems, such as in fluid dynamics, control theory, and population dynamics. They are also used in optimization problems, such as in portfolio management and optimal control. In addition, Riccati equations have applications in quantum mechanics, in the study of wave functions and Schrödinger's equation.

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