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Re: Solve / Reduce isolating results.

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  Re: Solve / Reduce isolating results. Bob Hanlon <hanlonr@cox.net> - 2011-04-30 09:53 +0000

#1932 — Re: Solve / Reduce isolating results.

eqns = {(1/6)*((SQ1*196)*2)^3 - (1/
         6)*((((2.75 + XX)*((3.75 + XX)*21^2))*100)*2)^3 == 
     1.2902698935932682*^18, (1/6)*((SQ1*100)*2)^3 - (1/
         6)*((((2.75 + XX)*((3.75 + XX)*21^2))*36)*2)^3 == 
     1.883856772422697*^17} // Rationalize[#, 0] &;

Solve[eqns, {SQ1, XX}, Reals]

{{SQ1 -> 5292, XX -> -(27/4)}, {SQ1 -> 5292, XX -> 1/4}}

Select[Solve[eqns, {SQ1, XX}], Element[#[[All, -1]], Reals] &]

{{SQ1 -> 5292, XX -> -(27/4)}, {SQ1 -> 5292, XX -> 1/4}}


Bob Hanlon

---- Lea Rebanks <lrebanks@netvigator.com> wrote: 

=============
Dear All,

Given the enclosed code - see below.
Please could someone help me setup the code to Solve / Reduce for these 2
missing values only required 

  {SQ1 -> 5292, 
    XX -> 0.25}

(I don't want multiple results.) I want positive numbers & NOT Complex..


Many thanks for your help & attention, really appreciated. Please see below.

Best regards,
Lea...
...................................................................


Clear[SQ1]
Clear[XX]
Solve[{(1/6)*((SQ1*196)*2)^3 - 
         (1/6)*((((2.75 + XX)*((3.75 + XX)*21^2))*100)*2)^3 == 
       1.2902698935932682*^18, (1/6)*((SQ1*100)*2)^3 - 
         (1/6)*((((2.75 + XX)*((3.75 + XX)*21^2))*36)*2)^3 == 
       1.883856772422697*^17}, {SQ1, XX}]

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