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Math Help - plwase help me check my answer!

  1. #1
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    plwase help me check my answer!

    I do.not have.the.answer.to this question, could.I.check.mine with yours?lg(75/16)-2lg(5/9)+lg(32/343), I got lg(486/343)...if I had gotten it wrong(most likely) could you please show me the working? Thankvyou so much
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    Re: plwase help me check my answer!

    Hey Tut.

    Doing the working out I get log(75/16) - 2log(5/9) + log(32/343) = log([75/16]/(25/81)*(32/343)) = log(194400/137200)

    Here is the working out from R.
    > 75*81*32
    [1] 194400
    > 16*25*343
    [1] 137200
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    Re: plwase help me check my answer!

    Thanks! I found.the answer key, it says its.lg2..
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    Re: plwase help me check my answer!

    Hello, Tutu!

    You gave us a problem with a typo . . .


    Simplify: .log(75/16) - 2log(5/9) + log(32/243)

    We have:
    . . \log\left(\frac{75}{16}\right) - \log\left(\frac{5}{9}\right)^2 + \log\left(\frac{32}{243}\right)

    . . . . =\;\log\left(\frac{75}{16}\right) - \log\left(\frac{25}{81}\right) + \log\left(\frac{32}{243}\right)

    . . . . =\;\log\left(\frac{75}{16} \div \frac{25}{81} \times \frac{32}{243}\right)

    . . . . =\;\log\left(\frac{{\color{blue}\rlap{//}}75^3}{{\color{green}\rlap{//}}16}\cdot\frac{{\color{red}\rlap{//}}81}{{\color{blue}\rlap{//}}25}\cdot \frac{{\color{green}\rlap{//}}32^2}{{\color{red}\rlap{///}}243_3}\right)

    . . . . =\;\log(2)
    Thanks from topsquark
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    Re: plwase help me check my answer!

    Quote Originally Posted by Tutu View Post
    Thanks! I found.the answer key, it says its.lg2..
    The answer key is wrong. Both of you have the correct solution, just written in a different form. (My answer is in a third form.) lg(2) can't be right because log(2) + 5 lg(3) - 3 log(7) does the job.

    -Dan
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    Re: plwase help me check my answer!

    Quote Originally Posted by topsquark View Post
    The answer key is wrong. Both of you have the correct solution, just written in a different form. (My answer is in a third form.) lg(2) can't be right because log(2) + 5 lg(3) - 3 log(7) does the job.

    -Dan
    Hmm....Seems I can't edit my post for some reason. Anyway, thanks for the catch Soroban. As always, nice job! (And I didn't see your solution before today.)

    -Dan
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