Re: Help w/ Mathematica: simple stuff
- To: mathgroup at smc.vnet.net
- Subject: [mg30876] Re: Help w/ Mathematica: simple stuff
- From: "Warren Wolfe" <wwolfe18 at home.com>
- Date: Fri, 21 Sep 2001 04:04:14 -0400 (EDT)
- References: <9nh2a1$iu$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"Daita Mizohu" <sophtwarez at yahoo.com> wrote in message news:9nh2a1$iu$1 at smc.vnet.net... > Hello all, > > I'm a mathematica novice and only doing basic calculus. We have a > question that is as follows: > > y[1]=a > y'[x]=(r*y[x])/x > > Explain Mathematica output of... > y[x]=ax^r > > I guess I don't understand what x is doing in the denominator. The > y[1]=a part is straight forward; when x is 1 then no matter what > constant r is it will be 1. I also know from my material that when > y[x]=kE^rx then y'[x]=r*y[x]. > > Thanks much, > > Daita, M. > y[x] = a*x^r IS the correct solution. To verify this calculate y'[x] and you get r*a*x^(r-1) which is the same as (r*a*x^r)/x which is r*y[x]/x Note that E^x plays no roll in the solution of this diffeq. Just execute DSolve[{y'[x]==(r*y[x])/x,y[1]==a},y[x],x] and all is well.