Re: Expansion symbolic

• To: mathgroup at smc.vnet.net
• Subject: [mg74797] Re: Expansion symbolic
• From: dh <dh at metrohm.ch>
• Date: Thu, 5 Apr 2007 04:15:56 -0400 (EDT)
• Organization: hispeed.ch
• References: <euvm0k\$cc5\$1@smc.vnet.net>

```
Hi Dominic,

Note, that output from TraditionalForm can not necessarily given as

input to Mathematica.

Daniel

Dominic Jackson wrote:

> Could anyone please tell me how to instruct Mathematica to expand the

> expression below with respect to the powers of x.  I would like the

> constants c1,c2,c3 and c4 to stay behind the summation sign but the powers

> of x to cross over to multiply x^(k+i).

>

>

>

> (c1 (x^2) +c2 (x^3))* D[(Summation sign i=0 to infinity) Subscript[a,i+1][k]

> * x^(k+i),{x,2}]//Expand.

>

>

>

> This is what I get

>

>

>

> c1 x^2 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k]

> * x^(k+i-2)

>

>

>

> + c2 x^3 *(Summation sign i=0 to infinity) (k+i)*(k+i-1)

> *Subscript[a,i+1][k] * x^(k+i-2)

>

>

>

> And this is what I want to achieve.

>

>

>

> c1 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] *

> x^(k+i)

>

>

> + c2 *(Summation sign i=0 to infinity) (k+i)*(k+i-1) *Subscript[a,i+1][k] *

> x^(k+i+1)

>

> Any clues.

> Thanx.

>

> Dom

>

```

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