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    cordov43's Avatar
    cordov43 Posts: 1, Reputation: 1
    New Member
     
    #1

    Jan 27, 2009, 09:00 PM
    math induction
    problem: math induction 1+27+125... +(2n-1)^3=n^2(2n^2-1)


    Please help!!
    juhi2011's Avatar
    juhi2011 Posts: 91, Reputation: 4
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    #2

    Jan 27, 2009, 09:04 PM

    1+27+125... +(2n-1)^3=n^2(2n^2-1)
    this can be expressed in the form :
    1^3+3^3+5^3... (2n-1)^3, now you can write the sum of the cubical equation using the formula and conclude the result...
    galactus's Avatar
    galactus Posts: 2,271, Reputation: 282
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    #3

    Jan 28, 2009, 04:32 PM


    Add to both sides:



    The right side becomes

    And the proof is complete.

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