-2.1.6 y'+2y =xe^{-2x}; y(1)=0

  • MHB
  • Thread starter karush
  • Start date
In summary, we used the integrating factor method to solve the differential equation $y^\prime + 2y = xe^{-2x}$ with initial condition $y(1)=0$. The integrating factor was determined to be $u(x)=e^{2x}$ and after distributing and simplifying, we obtained the solution $y=\frac{1}{2}(x^2-1)e^2$.
  • #1
karush
Gold Member
MHB
3,269
5
850
$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
$$u(x)=exp\int2 \, dx = e^{2x} $$
 
Last edited:
Physics news on Phys.org
  • #2
karush said:
$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
$$u(x)=exp\int2 \, dx = e^{2x} $$
What is the question?
 
  • #3
karush said:
is that correct

if so ill proceed

Your integrating factor is correct, but I would use the notation:

\(\displaystyle \mu(x)=\exp\left(2\int \,dx\right)=e^{2x}\)
 
  • #4
$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
$$u(x)=exp\int2 \, dx = e^{2x} $$

$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
obtain u(x)
$$u(x)=exp\int2 \, dx = e^{2x} $$
distribute
$$e^{2x} y'+e^{2x} 2y=e^{2x} xe^{2x}$$
simplify
$$\frac{dy}{dx}(e^{2x} (2y))= 4xe^x $$not sure

- - - Updated - - -

MarkFL said:
Your integrating factor is correct, but I would use the notation:

\(\displaystyle \mu(x)=\exp\left(2\int \,dx\right)=e^{2x}\)
ok

i kinda took some more steps but ...
 
  • #5
I think what you mean is:

\(\displaystyle \frac{d}{dx}\left(e^{2x}(2y)\right)\)

Please perform the indicated differentiation (product rule), and see if you get back to the previous step. :)
 
  • #6
$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
obtain u(x)
$$u(x)=exp\int2 \, dx = e^{2x} $$
distribute
$$e^{2x} y'+e^{2x} 2y=e^{2x} xe^{-2x}=x$$
simplify
$$ye^{(-2x)}=\int x dx = \frac{x^2}{2}+c$$
divide
$$y=\frac{x^2 e^{2x}}{2}+ce^{2x}$$
then
$$y(1)=\frac{e^{2}}{2}+ce^2=0 \therefore c=-\frac{1}{2}$$
finally
$$y=\frac{1}{2}(x^2-1)e^2$$

so any oops stuff
 
Last edited:

Related to -2.1.6 y'+2y =xe^{-2x}; y(1)=0

1. What does the equation "-2.1.6 y'+2y =xe^{-2x}; y(1)=0" represent?

This equation represents a first-order linear differential equation with an initial condition. It can be used to model a variety of real-world phenomena, such as population growth or chemical reactions.

2. How do you solve this differential equation?

To solve this equation, you can use the method of integrating factors. Multiply both sides by the integrating factor, e^2x, and then integrate both sides with respect to x. This will help you find the general solution, which can then be used to solve for the specific solution given the initial condition.

3. What is the purpose of the initial condition in this equation?

The initial condition, y(1)=0, gives us a specific point on the solution curve. This helps us determine the value of the constant of integration and find the unique solution to the differential equation.

4. How does the value of the constant of integration affect the solution?

The constant of integration is determined by the initial condition and can change the shape and position of the solution curve. Different values of the constant can result in different solutions that still satisfy the original differential equation.

5. Can this differential equation be used to make predictions about the behavior of a system?

Yes, this equation can be used to make predictions about the behavior of a system if the initial conditions and the values of the parameters in the equation are known. By solving the equation, we can find the specific solution that represents the behavior of the system over time.

Similar threads

  • Differential Equations
Replies
5
Views
1K
  • Differential Equations
Replies
10
Views
1K
  • Differential Equations
Replies
2
Views
2K
Replies
7
Views
2K
  • Differential Equations
Replies
2
Views
1K
  • Differential Equations
Replies
7
Views
2K
  • Differential Equations
Replies
5
Views
1K
Replies
9
Views
1K
  • Differential Equations
Replies
4
Views
3K
  • Differential Equations
Replies
7
Views
1K
Back
Top