Results 1 to 5 of 5

Math Help - Using an Exponent to Undo Log

  1. #1
    Super Member
    Joined
    Oct 2012
    From
    USA
    Posts
    738
    Thanks
    11

    Using an Exponent to Undo Log

    What is the next step in solving this (using this method)? But there is another way which involves using the log laws (which I know how to do).

    \log x - \dfrac{1}{3}\log8 = \log7

    10^{\log(x)- \frac{1}{3}\log8} = 10^{\log7}

    I believe the next step involves dividing the bases of the exponents, since the exponents are subtracted.
    Last edited by Jason76; June 28th 2013 at 09:25 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Jun 2013
    From
    india
    Posts
    34
    Thanks
    5

    Re: Using an Exponent to Undo Log

    why r u doing this???

    isnt log x=log7 +log2
    use log a + log b= log ab
    and find the answer
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member
    Joined
    Oct 2012
    From
    USA
    Posts
    738
    Thanks
    11

    Re: Using an Exponent to Undo Log

    An example of exponanted stuff:

    e^{\ln (2 + y^{2)}} = e^{\ln(4 + x^{2}) + C}

    2 + y^{2} = (4 + x^{2}) e^{C} Since adding, then multiplying comes in.

    But with the other example on this page, some subtracting was in there.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Jul 2012
    From
    INDIA
    Posts
    834
    Thanks
    209

    Re: Using an Exponent to Undo Log

    Do it with the laws of logarithms, you will get the answer straight unless you have a special purpose.
    lox x - 1/3 log 8 = log 7
    log x - log(8)^(1/3 ) = log 7
    log x - log 2 = log 7
    log ( x/2) = log 7 that will give x = 14
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,915
    Thanks
    779

    Re: Using an Exponent to Undo Log

    Hello, Jason76!

    \text{Solve for }x\!:\;\log x - \tfrac{1}{3}\log8 \:=\: \log7

    Simplify the logs before you exponentiate.

    We have: . \log x \:=\:\log 7 + \tfrac{1}{3}\log 8

    . . . . . . . . \log x \;=\;\log 7 + \log\left(8^{\frac{1}{3}}\right)

    . . . . . . . . \log x \;=\;\log 7 + \log 2

    . . . . . . . . \log x \;=\;\log(7\cdot2)

    . . . . . . . . \log x \;=\;\log 14

    Therefore: n . x \;=\;14
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: April 27th 2011, 05:53 PM
  2. [SOLVED] Help dividing exponent by exponent
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 29th 2010, 12:20 PM
  3. How would you undo these?
    Posted in the Algebra Forum
    Replies: 8
    Last Post: September 1st 2009, 07:29 PM
  4. Undo a mathematical conversion done inside a black box
    Posted in the Discrete Math Forum
    Replies: 0
    Last Post: February 10th 2009, 02:56 PM
  5. Replies: 1
    Last Post: August 19th 2008, 09:41 AM

Search Tags


/mathhelpforum @mathhelpforum