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Re: Solve equation with summation?


Not with my version

$Version

"8.0 for Mac OS X x86 (64-bit) (October 5, 2011)"

Solve[Sum[Subscript[a, i], {i, 1, n}]/x == 1, x]

{{x -> Sum[Subscript[a, i], {i, 1, n}]}}

Solve[Sum[Subscript[a, i]/x, {i, 1, n}] == 1, x]

{}


Bob Hanlon


On Fri, Nov 18, 2011 at 7:50 AM, Dr. Wolfgang Hintze <weh at snafu.de> wrote:
> Sorry, but with me both expressions (exactly copied from your message)
> give the same result.
> Regards,
> Wolfgang
>
> "Ivan" <iveney at gmail.com> schrieb im Newsbeitrag
> news:ja5f56$69e$1 at smc.vnet.net...
>> For a summation like \sum_{i=1}^n a_i/x = 1,
>>
>>  Solve[Sum[Subscript[a, i], {i, 1, n}]/x == 1, x]
>>
>> gives a correct solution.
>>
>> However, by putting x into the summation:
>>
>>  Solve[Sum[Subscript[a, i]/x, {i, 1, n}] == 1, x]
>>
>>
>> gives an empty set, why?
>>



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