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How do I do this watch

1. How do I work out

dy/dx + 9 = x(y-3)

I think its a first order differential equation but I'm not entirely sure about how to tackle this

Thanks
2. (Original post by SpaceBunny)
How do I work out

dy/dx + 9 = x(y-3)

I think its a first order differential equation but I'm not entirely sure about how to tackle this

Thanks
What methods do you know to solve first order differential equations?
3. (Original post by SeanFM)
What methods do you know to solve first order differential equations?
Methods? You mean like collecting all y terms onto one side and x on the other?
4. (Original post by SpaceBunny)
Methods? You mean like collecting all y terms onto one side and x on the other?
That sounds like a good one to use.
5. (Original post by SeanFM)
That sounds like a good one to use.
But I keep getting thrown off by that 9, really annoying me
6. (Original post by SpaceBunny)
But I keep getting thrown off by that 9, really annoying me
Woops, I was on autopilot, sorry!

Maybe seperating the variables isn't the way to go, and you may be better off expanding x(y-3) before using another method.
7. (Original post by SeanFM)
Woops, I was on autopilot, sorry!

Maybe seperating the variables isn't the way to go, and you may be better off expanding x(y-3) before using another method.
Ahh okay, thanks
8. (Original post by SpaceBunny)
How do I work out

dy/dx + 9 = x(y-3)

I think its a first order differential equation but I'm not entirely sure about how to tackle this

Thanks
Maybe multiply both sides by 1 / (y-3) and then multiply both sides by dx. Then take the integral of both sides and then get y on it's own.Not sure if what I said is even remotely related to working out the equation but that's all I could think of.
9. (Original post by SeanFM)
Woops, I was on autopilot, sorry!

Maybe seperating the variables isn't the way to go, and you may be better off expanding x(y-3) before using another method.
According to Wolfram, this can't be solved in terms of elementary functions
10. (Original post by Indeterminate)
According to Wolfram, this can't be solved in terms of elementary functions
that explains why I haven't been able to do it for the past few minutes. (Well, one of the reasons...)

Sorry, OP!
11. (Original post by SeanFM)
that explains why I haven't been able to do it for the past few minutes.

Sorry, OP!
I am pretty sure you have to integrate both sides simultaneously, after you get y and dy, and x and dx on separate sides of the equal sign.
12. this is a standard 1st order ODE which can be solved in 2 different ways using techniques available to further mathematicians

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