       • To: mathgroup at smc.vnet.net
• Subject: [mg35718] Re: Question about Replace
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Sat, 27 Jul 2002 06:43:23 -0400 (EDT)
• References: <7a.2a4ebef0.2a712bf7@aol.com> <ahr0mf\$l20\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```"Xuguang(Heather) Zhang" <xuguang_zhang at hotmail.com> wrote in message
news:ahr0mf\$l20\$1 at smc.vnet.net...
> Hi, Bob,
>
> I tried ReplaceRepeated, however, I got the following answer:
> x+y+z/(x+y)+e^(x+y)+(w*x)+y//. x+y->x
>
> e^x+x+(w*x)+2y+z/x
>
> In fact, there is still one more (x+y) term if we rewritten the answer.
That
> is e^x+(x+y)+y+(w*x)+z/x. Do you know how to get rid of it? Thanks.

Heather,

Use Simplify with the assumption x+y=x:

Simplify[x + y + z/(x + y) + e^(x + y) + w*x + y, {x + y == x}]

e^x + x + w*x + z/x

In other circumstances we may have to give more help Simplify (or
FullSimplify).
Please check possiblities in the Help Browser.

Allan

---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

```

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