Results 1 to 5 of 5

Math Help - Precalc HELP, ASAP. No idea, Please explain

  1. #1
    Newbie
    Joined
    Jul 2010
    From
    New Jersey
    Posts
    20

    Precalc HELP, ASAP. No idea, Please explain

    Solve leaving answers in terms of e or ln.

    a) e^(5x-3)=10



    b) 5^(3+x) = 20^x-3
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Mar 2009
    Posts
    378
    \ln basically undoes e. So if you want to isolate the exponent of e^x we can take the natural log like so \ln e^x = x. Now don't forget whatever you do to one side of an equation you have to do to the other side of the equation. Also, don't forget that \ln a^x = x\cdot \ln a. Make an attempt at these problems and post what you come up with.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jul 2010
    From
    New Jersey
    Posts
    20
    alright thank you!

    is this correct:

    5x - 3 = ln 10

    5x = ln 10 + 3

    x = [(ln 10) + 3] / 5
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member
    Joined
    Mar 2009
    Posts
    378
    Yep.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Jul 2010
    From
    New Jersey
    Posts
    20
    thank you, and for the second one, im stuck here but i have

    ln5 (3+x) = ln 20 (x-3)

    3 ln5 + x ln5 = x ln20 - 3 ln20

    3 ln5 + 3 ln20 = x(ln20 - ln5)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. precalc
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: February 22nd 2009, 10:17 AM
  2. precalc
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 22nd 2009, 01:07 AM
  3. precalc
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 21st 2009, 11:21 PM
  4. Precalc
    Posted in the Pre-Calculus Forum
    Replies: 0
    Last Post: October 26th 2008, 06:48 PM
  5. Precalc
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: August 25th 2008, 03:05 PM

Search Tags


/mathhelpforum @mathhelpforum