Results 1 to 5 of 5

Math Help - expanding logarithms?

  1. #1
    Newbie
    Joined
    Oct 2009
    Posts
    3

    expanding logarithms?

    I think this is called expanding... can someone explain how to work this one, please? TIA... SD

    Log [(BC)/AD]=
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Aug 2009
    From
    Israel
    Posts
    976
    Quote Originally Posted by sanddollar View Post
    I think this is called expanding... can someone explain how to work this one, please? TIA... SD

    Log [(BC)/AD]=
    Use these two rules:

    log(xy) = log(x) + log(y)
    log(\frac{x}{y}) = log(x) - log(y)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2009
    Posts
    3
    Here's what I did:

    log B + log C/log A + log D

    log B + log C - log A - log D

    Since the answers are given with log A first, I got
    -(log B + log C - log A - log D)

    log A - log B - log C + log D

    But it says it is not this answer. I can't see what I did wrong
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Mar 2007
    Posts
    1,240

    Talking

    What answer does the key provide?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,805
    Thanks
    115
    Quote Originally Posted by sanddollar View Post
    I think this is called expanding... can someone explain how to work this one, please? TIA... SD

    Log [(BC)/AD]=
    According to the arithmetic rules the given term is:

    \log\left(\dfrac {BC}{A} \cdot D\right) = \log(B)+\log(C) -\log(A) + \log(D)

    Rearranging:

    -\log(A)+\log(B)+\log(C)+\log(D)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Expanding
    Posted in the Algebra Forum
    Replies: 7
    Last Post: August 21st 2009, 02:15 PM
  2. expanding logarithms
    Posted in the Pre-Calculus Forum
    Replies: 10
    Last Post: March 11th 2009, 07:27 PM
  3. Help expanding log?
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 13th 2009, 05:31 PM
  4. expanding expression using properties of logarithms
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: November 21st 2008, 02:17 PM
  5. Expanding logarithms
    Posted in the Calculus Forum
    Replies: 4
    Last Post: September 24th 2008, 04:13 PM

Search Tags


/mathhelpforum @mathhelpforum