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Math Help - Adding algebraic exponents

  1. #1
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    Adding algebraic exponents

    Hi there,

    Can someone please show me how to solve the following equation:

    5^x + 25^(2x) = 150

    Any help will be greatly appreciated,

    Cheers
    Last edited by tazrulz99; November 13th 2007 at 09:02 PM.
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  2. #2
    Bar0n janvdl's Avatar
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    Quote Originally Posted by tazrulz99 View Post
    Hi there,

    Can someone please show me how to solve the following equation:

    5^x + 25^(2x) = 150

    Any help will be greatly appreciated,

    Cheers
    Hmm, just check that you didn't make a typo somewhere, it does look a bit like a hard equation for pre-algebra i would say.

    5^x + 25^{2x} = 150

    5^x + 5^{4x} = 150

    Set \ 5^x = k

    k + k^4 = 150

    k^4 + k - 150 = 0


    I quickly solved it by drawing a graph (See the attached image)

    And it seems the answers are -3,54 and 3.46
    Attached Thumbnails Attached Thumbnails Adding algebraic exponents-graph2.jpg  
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  3. #3
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    Ok and from there you solve with logs. Thanks!
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  4. #4
    Bar0n janvdl's Avatar
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    Quote Originally Posted by tazrulz99 View Post
    Ok and from there you solve with logs. Thanks!
    Yes because k = 5^x

    But 5^x cannot be equal to -3,54

    Thus 5^x = 3,46

    I found: x = 0,77
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