Did You Solve the Differential Equation Correctly?

  • Context: MHB 
  • Thread starter Thread starter karush
  • Start date Start date
Click For Summary
SUMMARY

The discussion centers on solving the first-order linear differential equation $$y' + 2y = xe^{-2x}$$ with the initial condition $$y(1) = 0$$. The integrating factor used is $$\mu(x) = e^{2x}$$, which is correctly identified. The solution process involves applying the product rule for differentiation and integrating to find the particular solution, resulting in $$y = \frac{1}{2}(x^2 - 1)e^{2}$$ after determining the constant of integration.

PREREQUISITES
  • Understanding of first-order linear differential equations
  • Knowledge of integrating factors in differential equations
  • Familiarity with the product rule of differentiation
  • Basic integration techniques, particularly for polynomial functions
NEXT STEPS
  • Study the method of integrating factors for solving linear differential equations
  • Learn about the product rule in calculus and its applications in differentiation
  • Explore initial value problems and their significance in differential equations
  • Investigate the behavior of solutions to differential equations as parameters change
USEFUL FOR

Students and professionals in mathematics, particularly those focusing on differential equations, as well as educators teaching calculus and differential equations concepts.

karush
Gold Member
MHB
Messages
3,240
Reaction score
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
karush said:
$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
$$u(x)=exp\int2 \, dx = e^{2x} $$
What is the question?
 
karush said:
is that correct

if so ill proceed

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

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

$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
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:

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

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

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

Please perform the indicated differentiation (product rule), and see if you get back to the previous step. :)
 
$$\displaystyle y^\prime +2y =xe^{-2x}, \quad y(1)=0$$
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:

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
7
Views
4K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
9
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K