Solving 1st Order Diff EQ: Check My Work for dy/dx = (3x+2y)/(3x+2y+2)

  • Thread starter JinM
  • Start date
  • Tags
    Diff eq
In summary, the conversation is about solving a separable differential equation, where the attempt at a solution involves using u = 3x+2y+2 and integrating with respect to u. The end result is a logarithmic function and a constant of integration. The conversation concludes with one person acknowledging their mistake and thanking the other for their help.
  • #1
JinM
66
0

Homework Statement



[itex]\frac{dy}{dx} = \frac{3x+2y}{3x+2y+2}[/itex]

2. The attempt at a solution

I thought I'd let u = 3x+2y+2, which would give me this,

[itex]u' = 5 - \frac{4}{u}[/itex]. This is seperable, and we thus get

[itex]\frac{1}{5}(3x + 2y +2) - \frac{4}{25}\ln|5(3x+2y+2)-4| = x + C[/itex]

Can someone check this? I've been differentiating this beast and I keep getting different coefficients. Is what I got here correct?
 
Last edited:
Physics news on Phys.org
  • #2
I get

[itex]\frac{1}{5}(3x + 2y +2) + \frac{4}{25}\ln|5(3x+2y+2)-4| = x + C[/itex]

Perhaps you should show me your steps when integrating

[itex]\int \frac{u}{5u-4} du[/itex]
 
  • #3
Gah, I actually missed TeXing the 5 inside the log function -- I got the same thing as you on paper. Thanks!
 

1. What is a first-order differential equation?

A first-order differential equation is a mathematical equation that relates an unknown function to its derivative (or rate of change). It involves only the first derivative of the unknown function and can be written in the form dy/dx = f(x,y).

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

To solve a first-order differential equation, you can use a variety of methods such as separation of variables, integrating factors, and substitution. The specific method used will depend on the form of the equation and any given initial conditions.

3. What is the purpose of checking my work when solving a first-order differential equation?

Checking your work when solving a first-order differential equation is important to ensure that your solution is correct and accurate. It allows you to catch any potential errors and make necessary corrections.

4. Can I use software or calculators to solve first-order differential equations?

Yes, there are many software programs and online calculators available that can solve first-order differential equations. However, it is still important to understand the steps and methods used to solve them manually.

5. What are some real-world applications of first-order differential equations?

First-order differential equations are used in many fields of science and engineering, such as physics, chemistry, biology, and economics. They can be used to model and predict the behavior of various systems and phenomena, such as population growth, chemical reactions, and electrical circuits.

Similar threads

  • Calculus and Beyond Homework Help
Replies
3
Views
247
Replies
2
Views
911
  • Calculus and Beyond Homework Help
Replies
11
Views
1K
  • Calculus and Beyond Homework Help
Replies
6
Views
1K
  • Calculus and Beyond Homework Help
Replies
21
Views
2K
  • Calculus and Beyond Homework Help
Replies
3
Views
28K
  • Calculus and Beyond Homework Help
Replies
3
Views
994
  • Calculus and Beyond Homework Help
Replies
1
Views
2K
  • Precalculus Mathematics Homework Help
Replies
8
Views
1K
  • Calculus and Beyond Homework Help
Replies
12
Views
1K
Back
Top