saadjumani
New member
- Joined
- Mar 30, 2019
- Messages
- 2
Hi, everyone. I had a test today and one of the questions was to solve the following equation:
y' + y = x
initial value was given as y(0) = 4.
I am newbie at differential equations and was not really that prepared for the test. So I just solved it the following way:
re-write the equation as:
dy/dx = x - y
=> dy = xdx - ydx
=> ∫ dy = ∫xdx - y∫dx
after integrating
=> y = (x^2)/2 - xy + c
then I proceeded to substituting the values y(0)=4. to find the value of C.
During discussion with a couple of my class mates, they said this approach to solution is wrong but I couldn't exactly understand why.
Can anyone explain whether it is really wrong. and if yes, why?
y' + y = x
initial value was given as y(0) = 4.
I am newbie at differential equations and was not really that prepared for the test. So I just solved it the following way:
re-write the equation as:
dy/dx = x - y
=> dy = xdx - ydx
=> ∫ dy = ∫xdx - y∫dx
after integrating
=> y = (x^2)/2 - xy + c
then I proceeded to substituting the values y(0)=4. to find the value of C.
During discussion with a couple of my class mates, they said this approach to solution is wrong but I couldn't exactly understand why.
Can anyone explain whether it is really wrong. and if yes, why?