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Maths question

  • 28-01-2014 8:11pm
    #1
    seandineen
    Registered Users Posts: 12 ✭


    Does anybody know how to show

    X^3-8
    ________
    X-2


    As a quadratic equation


Comments

  • #2
    Moody_mona
    Registered Users, Registered Users 2 Posts: 1,107 ✭✭✭Moody_mona


    Two options.

    1. Long division, diving the bottom into the top.

    2. Factorise the top, it's a difference between two cubes, and cancel.

    Factorising will be far quicker once you know how to do it.


  • #3
    Huell
    Closed Accounts Posts: 244 ✭✭Huell


    (x-2)(x^2+2x+4)
    ______________
    (x-2)

    and cancel your x-2 above and below line and you get x^2+2x+4


  • #4
    seandineen
    Registered Users Posts: 12 ✭seandineen


    Since ye seem to be maths geniuses on this does anybody know

    Given z=-2+i(square root of)5 , express z^2 in rectangular form


  • #5
    Moody_mona
    Registered Users, Registered Users 2 Posts: 1,107 ✭✭✭Moody_mona


    Write them as two brackets and multiply them algebraically.

    Remember sqrt(a) times sqrt(a) = a and that i^2=-1


  • #6
    spurious
    Moderators, Category Moderators, Education Moderators Posts: 27,240 CMod ✭✭✭✭spurious


    Please stop starting multiple threads on this. If you must, keep them all in the one thread, thanks.


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  • #7
    AHireland2k11
    Registered Users Posts: 173 ✭✭AHireland2k11


    I have a question for someone good at maths
    If z5=-3i, z4=6, z3=5-2i and z2=1-4i

    What is

    (Z5+z4)-(z3-z2)


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