Hi Guy's,(adsbygoogle = window.adsbygoogle || []).push({});

I have just started DE's and I'm having difficulty following my notes on using the substitution method. I was wondering if any one new a good link that could show me some good techniques to use when approaching these problems. Is there a good step by step process which any of you use?

An example in my notes says for

[itex]y'=\frac{y+2y}{y-sx}[/itex]

use the substitution [itex]u = \frac{y}{x}[/itex]

ie

[itex]y = ux[/itex]

Is there a reason why they chose [itex]u = \frac{y}{x}[/itex] ?

regards

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# Introduction to substitutions

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