problem writing a simple equation--urgent!!!

*To*: mathgroup at smc.vnet.net*Subject*: [mg50359] problem writing a simple equation--urgent!!!*From*: erkenays at yahoo.com (aysegul)*Date*: Sun, 29 Aug 2004 03:54:07 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi all, I have a problem about writing an equation in mathematica. I am writing the following equation: u[x_, y_] = x + 2*y and when I write for example u[2,4] , it gives the result. But the problem that I have is expressing this equation with parameters. That is u[x[1], x[2]] = x[1] + 2*x[2] but when I ask u[2,4]; it gives u[2,4] result.It doesn't calculate. So, how can I write this equation? Thanks all.

**Follow-Ups**:**Re: problem writing a simple equation--urgent!!!***From:*DrBob <drbob@bigfoot.com>