Results 1 to 3 of 3

Math Help - logs

  1. #1
    Junior Member
    Joined
    May 2007
    Posts
    31

    Post logs

    are my answers right? they're due tomorrow

    evaluate: log(2)1/16
    i got -2.3344

    solve for x: e^(x-2)=10
    i got 4.30 = x

    solve for x: 2log(3)x - log(3)2 = log(3)8
    i got x = 4
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie Logarithm Freak's Avatar
    Joined
    May 2007
    From
    Houston, Texas
    Posts
    3
    evaluate: log(2)1/16
    i got -2.3344

    solve for x: e^(x-2)=10
    i got 4.30 = x

    solve for x: 2log(3)x - log(3)2 = log(3)8
    i got x = 4

    (note: I'm assuming that the (2) is for base 2)

    (Log1/16)/(Log2)
    -4


    Ln(e^x-2)= ln10
    x-2= ln10
    x-2+2= 2.3025 + 2
    x= 4.3025
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,904
    Thanks
    765
    Hello, trancefanatic!

    Evaluate: .log2(1/16)
    We have: .log2(1/16) .= .log2(1/2^4) .= .log2(2^{-4}) .= .-4


    Solve for x: .e^{x-2} .= .10
    i got: x = 4.30 . Right!
    Take logs of both sides: .ln[e^{x-2}] .= .ln(10)

    Then we have: .(x-2)·ln(e) .= .ln(10)

    Since ln(e) = 1, we get: .x - 2 .= .ln(10)

    Therefore: .x .= .ln(10) + 2 . .4.30



    Solve for x: .2·log3(x) - log3(2) .= .log3(8)
    I got: x = 4 . Yes!
    We have: .log3(x˛) - log3(2) .= .log3(8)

    . . . . . . . .log
    3(x˛) .= .log3(8) + log3(2) .= .log3(8·2) .= .log3(16)

    Then: . .= .16 . . . . x .= .±4

    But x = -4 is an extraneous root.
    The only solution is: .x = 4

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 9
    Last Post: February 22nd 2011, 06:39 PM
  2. Logs
    Posted in the Algebra Forum
    Replies: 4
    Last Post: April 24th 2010, 08:52 AM
  3. Logs
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: October 10th 2009, 07:08 PM
  4. Dealing with Logs and Natural Logs
    Posted in the Advanced Algebra Forum
    Replies: 0
    Last Post: April 14th 2008, 07:18 AM
  5. several questions-logs/natural logs
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: November 12th 2007, 09:58 PM

Search Tags


/mathhelpforum @mathhelpforum