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Re: Why isn't Expand[] grouping terms by order?

• To: mathgroup at smc.vnet.net
• Subject: [mg87862] Re: Why isn't Expand[] grouping terms by order?
• From: Peter Breitfeld <phbrf at t-online.de>
• Date: Sat, 19 Apr 2008 03:31:35 -0400 (EDT)
• References: <fu9fq7$cbn$1@smc.vnet.net>

<p at dirac.org> schrieb:
> Consider this:
>
>    In[19]:= Expand[ (1+a*x)*(1+b*x), x]
>
>                                  2
>    Out[19]= 1 + a x + b x + a b x
>
>
> How can I coax Mathematica to give me this, instead:
>
>                                  2
>    Want[19]= 1 + (a + b) x + a b x
>
> Why isn't Mathematica reporting the answer in terms of powers of x?
>
> Thanks!
>

expr = (1 + a x) (1 + b x)

Collect[expr,x]

Gruss Peter
-- 
==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de