Yahoo Answers is shutting down on 4 May 2021 (Eastern Time) and the Yahoo Answers website is now in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
First order linear differential equations help?
How do I solve this differential equation using the first order linear differential equations?
dy + 3ydx = e^(-3x) dx
3 Answers
- cidyahLv 710 years agoFavourite answer
divide by dx
dy/dx + 3y = e^(-3x) -----------(1)
Equation of the form dy/dx +yp(x)=q(x)
p(x)=3
q(x)=e^(-3x)
Compute the integrating factor e^∫p(x) dx = e^∫3 dx = e^(3x)
Multiply both sides of (1) by the integraing factor e^(3x)
e^(3x) dy/dx + 3y e^(3x) = e^(-3x)e^(3x)
e^(3x) dy/dx + 3y e^(3x) = 1 --------(2)
The left side of (2) is the derivative of ye^(3x) or [ye^(3x)]'
(2) may be written as
[ye^(3x)] ' = 1
Integrate both sides
∫[ye^(3x)] ' = ∫ 1 dx
y e^(3x) = x + C
divide both sides by e^(3x)
y = x e^(-3x) + C e^(-3x)
- 10 years ago
Lol so easy
jst divide by dy
u wil get
1 + 3y (dx/dy) =e^(-3x) (dx/dy)
nw after arranging
(e^(-3x) - 3y ) (dx/dy) = 1
nw
dx/dy = (1 / (whole thing) )
this is simplified and i hope u can solve next steps
- Anonymous5 years ago
2(dy/dx) = 5 - 6y This is actually seperable: dy/(5 - 6y) = dx/x Integrating both sides: -1/6*ln|5 - 6y| = ln|x| + C solve for y.