#š
20 messages Ā· Page 1 of 1 (latest)
- Wait patiently for a helper to come along.
- Once someone helps you, say thank you and close the thread with:
+close
- Feel free to nominate the person for helper of the week in #helper-nominations
- Do not ping the mods, unless someone is breaking the rules.
- If you're happy with the help you got here, and the server overall, you can contribute financially as well:
I think you forgot to multiply the -2(x - 2)^2 term when moving it to the RHS.
Anyway, seems mostly ok apart from that, though you do have some strange expressions at the end. Here's an quicker way to do it.
(x - 2)y' - y = 2(x - 2)^3
((x - 2)y' - y)/(x - 2)^2 = 2(x - 2)
(y/(x - 2))' = 2(x - 2)
Then integrate and express y.
This is actually what my friend sent me i did it in this way but im stuck
Can u please tell me what i did is right?
Oh, the general formula. Was it like this, though? Let me check.
U can do it in two ways find the integrating factor and mulitiply the eq1 with it or use the general form
Those aren't the only ways. At least, you can write it in another way, even without using the shortcut for this case that I did above.
Im stuck at that integral step
So what i did is right also?
This is the general formula for y' + f(x)y = g(x). Note that the integrals are taken as antiderivatives, so without C.
We have:
f(x) = -1/(x - 2)
g(x) = 2(x - 2)
ā«(f(x)dx) = -ln(|x - 2|)
e^(-ā«(f(x)dx)) = x - 2
g(x)e^(ā«(f(x)dx)) = 2(x - 2)/(x - 2) = 2
ā«(g(x)e^(ā«(f(x)dx))dx) = 2x
So:
y = (x - 2)(C + 2x)
I'm not sure what expressions you have near the end. The result is correct, so just try writing it a bit more clearly.
As for what general approach I prefer: solving the homogeneous equation, then using variation of parameters.
Like the one my friend did?
Well, your friend just used the general formula.
It will come from any approach, but it might not be easy to remember.
Thank you so much I appreciate it
@crude yoke has given 1 rep to @inland copper