Solving a first order differential equation

In summary, the conversation is about solving a differential equation (dy/dx = 2/(x+e^y)). The attempt at a solution involved using the substitution v=x+e^y, but the user did not make much progress. Another user suggested setting v=ux to simplify the equation to a linear differential equation. A third user suggested using the result dy/dx=1/(dx/dy) to find y in terms of x.
  • #1
fred_91
39
0

Homework Statement



Solve the differential equation:
dy/dx = 2/(x+e^y)

Homework Equations

The Attempt at a Solution



I tried to use the substitution v=x+e^y, but I didn't get very far:

v’=1+e^y y’
v’-1=(v-x)y'
y’ = (v’-1)/(v-x)
(v’-1)/(v-x) (x+v-x)=2
V (v’-1)/(v-x)=2
vv’-v=2(v-x)
vv’-3v=-2x

any help will be very much appreciated.
 
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  • #2
fred_91 said:

Homework Statement



Solve the differential equation:
dy/dx = 2/(x+e^y)
Threads for solving differential equations by nature belong in the Calculus HW forum.
 
  • #3
fred_91 said:
vv’-3v=-2x
Hmm, this last equation is homogeneous, so setting v=ux should allow you to separate variables.
 
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  • #4
fred_91
hi
use this result to simplify it to a linear differential equation
dy/dx=1/(dx/dy)
 
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  • #5
2nafish117 said:
fred_91
hi
use this result to simplify it to a linear differential equation
dy/dx=1/(dx/dy)
Oh yes! This works very nicely.

Use it with the given D.E.
 

Related to Solving a first order differential equation

1. What is a first order differential equation?

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

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

To solve a first order differential equation, you need to find an expression for y that satisfies the equation. This can be done by using various methods such as separation of variables, integrating factors, or variation of parameters.

3. What is the difference between an explicit and implicit solution to a first order differential equation?

An explicit solution expresses y as a function of x, while an implicit solution does not explicitly define y in terms of x. Instead, it involves an implicit relationship between x and y.

4. Can a first order differential equation have multiple solutions?

Yes, a first order differential equation can have infinitely many solutions. This is because the equation represents a family of curves, and each curve in the family is a solution.

5. How can solving a first order differential equation be applied in real life?

Solving first order differential equations is a powerful tool in understanding and predicting the behavior of many natural phenomena such as population growth, chemical reactions, and electrical circuits. It is also used extensively in engineering, physics, and other scientific fields.

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