maths question- logarithm

  1. #1
    madmikejt12 is offline Dedicated Member

    maths question- logarithm

    does anybody know anything about these?

    I have an asignment here and im baffled by this one:

    Reduce the following to a single logarithm:

    2log 2 - 3log 4 + log 6

    could someone please show me how to do it?

    also this one:

    x= log4 2

    (The RED "4" should be in subscript format but it is not working)
    Last edited by madmikejt12; 24-12-2007 at 04:11 PM.


  2. #2
    jephree is offline ¨*·.¸ «.·°·..·°·.» ¸.·*¨
    This should help on the first problem:

    http://web.rollins.edu/~dchild/SMGSi...uide/Logs.html

    The answer to the second is:

    log4 2 = 0.50

    (assuming base 10)


    Many guides and calculators found with Google:

    http://www.google.com/search?sourcei...f8&q=logarithm


    ...
    Last edited by jephree; 24-12-2007 at 07:05 PM.

  3. #3
    madmikejt12 is offline Dedicated Member
    Thanks for the reply

    i got 0.5 for the second one before when i tries it, wasnt sure if it was right though...

    i used:

    Log10 2/Log10 4

    Blue number= Base


    I am still unsure about how to go about the 1st one
    Do i need to make all the bases equal and then add them? if so how?
    We didnt have time to go over logarithms on our college day, we were to buisy going over GCSE level stuff which i had already answered and the asignment is due in when we go back! (along with 5 others!!!)

    Also what is Ln? Q4 is all about logarithms and indicies and the last part just says:

    Solve for x
    y=ln(x)
    Last edited by madmikejt12; 24-12-2007 at 07:38 PM.

  4. #4
    jephree is offline ¨*·.¸ «.·°·..·°·.» ¸.·*¨
    natural logarithm (loge, ln, log, or Ln) in mathematical analysis, statistics, economics and some engineering fields. The reasons to consider e the natural base for logarithms, though perhaps not obvious, are numerous and compelling.
    common logarithm (log10 or simply log; sometimes lg) in various engineering fields, especially for power levels and power ratios, such as acoustical sound pressure, and in logarithm tables to be used to simplify hand calculations
    binary logarithm (log2; sometimes lg, lb, or ld) in information theory and computer-related fields
    indefinite logarithm when the base is irrelevant, e.g. in complexity theory when describing the asymptotic behavior of algorithms in big O notation.
    http://en.wikipedia.org/wiki/Logarithm

    I used a calculator. I probably know less than you as it has been many years since I did this stuff.

    I don't fully understand the notation:

    2log 2 - 3log 4 + log 6


    Unless it equates to log2 2 - log3 4 + log 6

    Yet log 6 has no base

    I didn't try this calculator but it appears to handle and simplify equations:

    http://web.rollins.edu/~dchild/SMGSi...uide/Logs.html

  5. #5
    madmikejt12 is offline Dedicated Member
    Yet log 6 has no base
    the 6 is the base isnt it?

    like the 2 and the 4
    Nevermind that, im getting confused.... i dont have a clue really!!

    i wrote it slightly wrong in the 1st post, there should be no spaces before the numbers:

    2log2 - 3log4 + log6

    In my notes it says "log bn"
    Where b=base and is "subscripted"
    Last edited by madmikejt12; 24-12-2007 at 08:37 PM.

  6. #6
    DevilsAdvocate is offline Elite Member
    And to think people reckon that these days the geeks shall inherit the earth... They've clearly never heard of John Napier, ÜberGeek!!

  7. #7
    madmikejt12 is offline Dedicated Member
    2log2-3log4+log6 can also be written as:

    log2^2-log4^3+log6

    Does this help? Still cant figure out what to do with it!!!

  8. #8
    Tassie Devil is offline DAL Aussie Contingent
    2log2 - (3log4 + log6) = -1.98

    I had to wait for hubby to come home, I know zilch about this stuff. The above equation is how he entered it into a calculator. Hope it makes sense to you cause it doesn't to me.

  9. #9
    madmikejt12 is offline Dedicated Member
    Thank you for the reply
    but sorry, the question is asking me to reduce it to a sinle logarithm


  10. #10
    jephree is offline ¨*·.¸ «.·°·..·°·.» ¸.·*¨
    Using the formula for addition and subtraction I get this:

    log(A) + log(B) -> log(A x B)

    log(A) - log(B) -> log(A/B)

    log2^2/4^3 + log6

    log2^2/4^3 x 6


    ...perhaps the DA will send John Napier by this way.

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