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Math Help - find x (exponant)

  1. #1
    Junior Member
    Joined
    Oct 2005
    Posts
    29

    ook..

    given that 4^x=8^2-x find the value of x (x is a power)

    ooook see what u can do
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  2. #2
    MHF Contributor
    Joined
    Apr 2005
    Posts
    1,631
    x is a power.
    Okay.

    4^x = 8^(2-x)
    (2^2)^x = (2^3)^(2-x)
    2^(2*x) = 2^[3(2-x)]
    2x = 3(2-x)
    2x = 6 -3x
    2x +3x = 6
    5x = 6
    x = 6/5 ---------answer.

    Check,
    4^x = 8^(2-x)
    4^(6/5) =? 8^(2 -6/5)
    4^(1.2) =? 8^(0.8)
    Using a calculator,
    5.278031643 =? 5.278031643
    Yes, so, OK.
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  3. #3
    Junior Member
    Joined
    Oct 2005
    Posts
    29
    thanks a lot
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