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    mstehman88's Avatar
    mstehman88 Posts: 3, Reputation: 1
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    #1

    May 12, 2009, 11:32 AM
    Two logarithmic Equation Questions!
    I need help on solving the 2 log equations I attached to this message, I may have got the second one done but need to check it.

    1. is Log base 10 to the x = log base 3 to the 9



    2. 9 to the 7-3x = 5


    Please let me know how to work them both out by an image or step by step text.

    Thank you!
    Matt
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    Perito's Avatar
    Perito Posts: 3,139, Reputation: 150
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    #2

    May 12, 2009, 11:46 AM
    Quote Originally Posted by ;
    is Log base 10 to the x = log base 3 to the 9
    Is this what you mean? Log base 10 of x = log base 3 of 9?



    The important identity to remember is this one:



    so



    make that substitution and solve for x. Unknown008 noted that 9 is a whole-number log of 3. That's a better way to do the problem if you see that.

    #2:








    Is this what you got?
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #3

    May 12, 2009, 11:46 AM

    1.Ok, firstly,













    You should know your index - log relation;





    2. Use the formula gave to have





    Type the value of log_9 5 in your calculator and solve for x

    Did that help? :)
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #4

    May 12, 2009, 11:48 AM
    LOL Perito! :p

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