Solve for x in cubed polynomial equation

Discussion in 'Algebra' started by randyoy, Oct 12, 2021.

  1. randyoy

    randyoy

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    Hi, Attempting to solver for x:

    y=5/6 * x * (2x^2 +27x +91)
     
    randyoy, Oct 12, 2021
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  2. randyoy

    MathLover1

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    y=(5/6) x*(2x^2 +27x +91) .....factor 2x^2 +27x +91

    2x^2 +27x +91
    =2x^2 +14x+13x +91
    =(2x^2 +14x)+(13x +91)
    =2x(x +7)+13(x +7)
    =(x + 7) (2 x + 13)
    y=(5/6) x*(x + 7) (2 x + 13)
    so, you have

    set y=0

    (5/6) x*(x + 7) (2 x + 13) =0

    equal each factor to 0

    (5/6) x =0 => x=0

    (x + 7) = 0 => x=-7

    (2 x + 13) =0 => x=-13/2


    upload_2021-10-12_11-37-55.png
     
    MathLover1, Oct 12, 2021
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    nycmathguy likes this.
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  3. randyoy

    nycmathguy

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    Nicely done.
     
    nycmathguy, Oct 13, 2021
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