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Finding the power using logarithm

  1. Jan 28, 2007 #1

    disregardthat

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    Actually, I am trying to use what I have learned on school to something else

    1. The problem statement, all variables and given/known data

    3*10^x = 1.73*10^14

    2. Relevant equations

    lga^x = xlga

    3. The attempt at a solution

    10^x = (1.73 * 10^14)/3
    10^x = 5.767 * 10^13
    xlg10 = 13lg(57.67)

    x=13lg(57.67)
    x=22.89

    :\

    3 * 10^22.89 = 1.73 * 10^14 is certainly not correct..
    What am I doing wrong?

    I tried this too:
    x=5.767 * 13lg(10)
    x=5.767 * 13
    x = 74.971

    And that is even more incorrect!
     
    Last edited: Jan 28, 2007
  2. jcsd
  3. Jan 28, 2007 #2

    arildno

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    Answer my question, please!
     
  4. Jan 28, 2007 #3

    disregardthat

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    i know that if a=b, then lga = lgb
    and lga^x=xlga

    then i just took the ^13 on the other hand of lg.5.767*10, an made that 13lg5.767*10) and that is 13lg57.67

    But if that is incorrect, I tryed it the other way underneath. How am I supposed to get the right answer?

    EDIT: I found out the right answer now.

    I took the lg(0.576*10^14) and that became 13.76

    and 3*10^13,76 is approximately 1.73*10^14
     
    Last edited: Jan 28, 2007
  5. Jan 28, 2007 #4

    arildno

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    Questions:

    1. Do you see any difference between the expressions:
    [itex](5.767*10)^{13}[/itex] and [itex]5.767*(10^{13})[/itex]?

    2. Do you see any relevance of 1. to the issue at hand?
     
  6. Jan 28, 2007 #5

    disregardthat

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    I saw the difference, and I got my answer correct.

    What do you mean by the number 2. I didn't uderstand :confused:
     
  7. Jan 29, 2007 #6

    HallsofIvy

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    He was asking you if you saw why that difference was important!
     
  8. Jan 30, 2007 #7

    disregardthat

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    I saw the difference afterwards :)
     
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