Odd CFactorise result in miss-CAS-interpretation?

Liliana shared this problem 7 years ago
Answered

Hi!

Perhaps to go on with the same ticket of one of several sintoms of this type of unexpected results? As https://jira.geogebra.org/b... Perhaps it could be more straight than the tactic of dividing sintoms of the same problem in multiple tickets spread around locked questions?

    GeoGebra 4.9.104.0-JOGL1 (14 February 2013) Java: 1.7.0_09

    Being:

    eo_1 := 1/ (sqrt(1/7) (2 x + ? sqrt(3))) and

    eo_1 := 1/ (sqrt(1/7) (2 x + ? sqrt(3)))

    CommonDenominator[eo_1,eu_1] gives sqrt(21) - 2sqrt(7) x ? + 3sqrt(3) x² ? + 6x³

    CFactorise[sqrt(21) - 2sqrt(7) x ? + 3sqrt(3) x² ? + 6x³] gives (

    3x² - ? sqrt(7)) (2x + ? sqrt(3))

    But...

    CFactorise[CommonDenominator[eo_1,eu_1]] gives

    (9x? + 7) (4x² + 3)

    Same thing in

      GeoGebra 4.2.19.0 (08 February 2013) Java: 1.7.0_09

      Thanks so much for any explicative answer. Cheers,

      Liliana


      [size=85]One of them... such as the previous:

      Being ex_1 := (1 / (2 x - 3 p)) and ex_2 := (3 / (4 x² - 4 x p + p x))

      CommonDenominator[ex_1, ex_2] gives 9p² x - 18p x² + 8x³

      Factorise[9p² x - 18p x² + 8x³] gives (4x - 3p) (2x - 3p) x

      But...

      Factorise[CommonDenominator[ex_1,ex_2]] gives 1


      But... in

        GeoGebra 4.2.19.0 (08 February 2013) Java: 1.7.0_09

        Factorise[CommonDenominator[ex_1, ex_2]] gives a correct result

        (3p - 2x) (3p - 4x) x

        However, in both GG versions...

        Factorise[CommonDenominator[ (1 / (2 x - 3 p)), (3 / (4 x² - 4 x p + p x)) ]] gives 1


        Thanks in advance for any answer. Cheers,

        Liliana[/size]

Comments (2)

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1

08c158bec09aee5a7c773b81dc3fc512... and also CIFactor

CIFactor[(-x) / 4 pi² + ί sqrt(3 + x) / 2 + x² + 3 / 4] gives -(π + sqrt(4x³ - sqrt(-12 x² - 4x³) + 3x) / x) ("sym2poly/r2sym(const gen & e,const index_m & i,const vecteur & l) Error: Bad Argument Value" + "sym2poly/r2sym(const gen & e,const index_m & i,const vecteur & l) Error: Bad Argument Value") / 4


Thanks in advance. Take care,

Liliana

https://ggbm.at/562531

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