Results 1 to 3 of 3

Math Help - Solve for X in equations

  1. #1
    Newbie
    Joined
    Aug 2007
    Posts
    6

    Solve for X in equations

    Solve for x in each equation. Question 1. e^{5x} = 46.38^{(2.6)} Question 2. e^x-e^{-x}=4
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by oldschool999 View Post
    Solve for x in each equation. Question 1. e^{5x} = 46.38^{(2.6)} Question 2. e^x-e^{-x}=4
    1. Take natural logs:

    e^{5x} = 46.38^{(2.6)}

    then:

    5x = 2.6 \ln(46.38)

    so:

    x=0.52~ \ln(46.38)

    RonL
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by oldschool999 View Post
    Solve for x in each equation. Question 1. e^{5x} = 46.38^{(2.6)} Question 2. e^x-e^{-x}=4
    Question 2:

    Multiply through by e^x

    e^x-e^{-x}=4

    so:

     e^{2x}-1=4 e^x

    then let y=e^x so:

    <br />
y^2-4y-1=0<br />

    solving this gives y=2 \pm \sqrt{5}, but as y>0 only y=2+\sqrt{5} is a valid solution if we want x to be real. Then x=\ln(2+\sqrt{5})

    RonL
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. How should I solve these equations?
    Posted in the Algebra Forum
    Replies: 3
    Last Post: February 21st 2011, 04:20 AM
  2. Solve the following equations for 0<x<360 ?
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: January 31st 2011, 12:33 AM
  3. solve the equations
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: October 28th 2009, 04:41 AM
  4. May someone solve this equations for me?
    Posted in the Algebra Forum
    Replies: 2
    Last Post: February 14th 2009, 05:44 PM
  5. Solve the following equations
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: December 10th 2008, 05:22 PM

Search Tags


/mathhelpforum @mathhelpforum