maths

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x is a number such that x2+3x+9=0. What is the value of x3?

  • maths -

    since (x-3)(x^2+3x+9) = x^3 - 3^3
    x^3 - 3^3 = 0
    x^3 = 27

  • WoW at Steve - maths -

    What a great way to do this question.

    Did you see the round-about way I used ??
    http://www.jiskha.com/display.cgi?id=1360597831

    I was even thinking of using DeMoivre's theorem.

  • WoW at Reiny - maths -

    I was going to show an alternative direct solution, but when I saw where it was headed, I blew it off.

    Can't believe you
    (a) slogged through it all
    (b) got it right!

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