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-   -   Logrithmic functions (https://www.askmehelpdesk.com/showthread.php?t=66731)

  • Feb 26, 2007, 05:31 PM
    w86lynn
    Logrithmic functions
    I'm having trouble with these problems if someone could help me that would be great.

    2^(3x-5)=4
    27^(7x-3)=3^(20x+19)
    log X + log 4= log 5
  • Feb 26, 2007, 09:19 PM
    cool_dude
    you just need to know some rules(properties) of logarithms and you can solve it.

    1) 2^3x-5 = 4
    3x-5log2 = log 4 (pay attention to this property. You take the log of both sides and
    3x = log 4 + 5log2 exponents come down)
    x = (log 4 + 5log2) / 3

    2) 27^7x-3 = 3^20x+19
    use the same property as in question 1 and you'll get it. Post your answer if you want me to verify it for you

    3)logx + log4 = log5
    this is another property.
    log x = log 5 - log 4
    10 ^ log5-log4 = x (this is another property)

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