Differential Equations Ordinary and Partial Differential Equations Math Forum

 November 11th, 2011, 12:24 AM #1 Newbie   Joined: Nov 2011 Posts: 4 Thanks: 0 Differential equation simplification Hi. Just need some help understanding how my tutor simplified a differential equation and what laws he used to get his answer. The question is: e^(y/x)y'=2(e^(y/x)-1)+(y/x)e^(y/x) - use the substitution y=xv(x) to solve this. I can post my whole working if you need to see it but basically both mine and the tutors answers simplify to this point ln|e^v-1|=ln|x^2|+c Now i would simplify this to e^v-1=x^2+e^c but I am clearly doing something wrong because my tutor gets ln|e^v-1|=x^2*e^c which then somehow simplifies to cx^2 some basic law seems to be hovering just out of reach. Would appreciate an explanation. Thanks! November 11th, 2011, 03:19 AM #2 Newbie   Joined: Oct 2011 Posts: 26 Thanks: 0 Re: Differential equation simplification where is a constant November 12th, 2011, 08:25 PM #3 Global Moderator   Joined: Dec 2006 Posts: 21,105 Thanks: 2324 If y is defined for all real x, �where the constants A and B are non-negative. I'll leave you to specify the domain if the constants are not both non-negative. Tags differential, equation, simplification Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post TastyLemons Linear Algebra 0 February 2nd, 2014 10:54 PM PhizKid Differential Equations 0 February 24th, 2013 11:30 AM mathbalarka Differential Equations 2 January 2nd, 2013 01:01 AM Vasily Differential Equations 10 April 9th, 2012 07:06 AM MathForFun Advanced Statistics 1 September 1st, 2009 11:05 PM

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