solve differential equation problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg68820] solve differential equation problem*From*: "elvis" <rapstone at gmail.com>*Date*: Sun, 20 Aug 2006 04:43:39 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Here we often use mathematica to solve differential equations, when I encouter a equation with several constrains I set them to those values. But it cannot solve it and have the following warnings: DSolve::deqx: Supplied equations are not differential equations of the given functions. Give a very simple differential equation here: DSolve[{y'[x] == r*y[x], y[0] == a}, y, x] Can anyone help to "solve" this problem for me? Thanks!