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Re: Series[] command

• To: mathgroup at smc.vnet.net
• Subject: [mg55952] Re: Series[] command
• From: dh <dh at metrohm.ch>
• Date: Tue, 12 Apr 2005 05:26:01 -0400 (EDT)
• References: <d3cq8l$6er$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Hello Kris,
The equivalence of two expressions is in general a non-solvable problem, 
but in your case you can convince yourself that the two expression are 
equivalent by:

ma*mb + ma(b-mb) + mb(a-ma) + (a-ma)(b-mb) == b(a-ma) + ma(b-mb) + ma*mb 
//simplify

what gives True.

Sincerely, Daniel

Kris Preacher wrote:
> Hi all,
> 
> I need to obtain the second-order Taylor series expansion of a*b around the
> points ma and mb. I thought Mathematica's Series[] command would do the
> trick, but no. The correct answer is:
> 
> ma*mb + ma(b-mb) + mb(a-ma) + (a-ma)(b-mb)
> 
> Mathematica gives:
> 
> b(a-ma) + ma(b-mb) + ma*mb
> 
> Whaddup??
> 
> Thanks,
> Kris Preacher
> UNC
> 
>