• Support PF! Buy your school textbooks, materials and every day products Here!

Linear DE

  • Thread starter nateshoe
  • Start date
  • #1
9
0
1. Homework Statement [/b]
y'=4x–y+4; y(0)=8

2. The attempt at a solution[/b]
This is simply a first-order DE
So:

y'+y=4x+4
P(x)=1
Q(x)=4x+4
p(x)=e^x
So that ends up being:

ye^x=(4xe^x+4e^x)dx

Integration:
ye^x=4xe^x-4e^x+4e^x

ye^x=4xe^x
divide by e^x
y=4x+C
y=4x+8


However it tells me I'm wrong. either I'm very stupid or I'm going about this completely wrong.

Thanks,
Nate
 

Answers and Replies

  • #2
mjsd
Homework Helper
726
3
note after the integration, you pick up a constant
[tex]y e^x = 4 x e^x + C[/tex]
 
  • #3
9
0
Appreciate it!
 

Related Threads on Linear DE

  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
1
Views
394
  • Last Post
Replies
5
Views
1K
  • Last Post
Replies
9
Views
2K
  • Last Post
Replies
3
Views
685
Replies
2
Views
864
Replies
0
Views
4K
  • Last Post
Replies
4
Views
853
  • Last Post
Replies
2
Views
954
  • Last Post
Replies
4
Views
2K
Top