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Math Help - Solving Exponential Equations

  1. #1
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    Solving Exponential Equations

    Can someone help me solve this equation
    e^x=x+2

    P.S
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  2. #2
    Member mybrohshi5's Avatar
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    Are you sure that is the correct problem? Just making sure cause i just took a shot at it and i cannot figure it out....
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  3. #3
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    Quote Originally Posted by Paymemoney View Post
    Can someone help me solve this equation
    e^x=x+2

    P.S
    In short, it can't be solved exactly.

    You would have to use Numerical methods like the Bisection Method or Newton's Method.
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  4. #4
    Member mybrohshi5's Avatar
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    Quote Originally Posted by Prove It View Post
    In short, it can't be solved exactly.

    You would have to use Numerical methods like the Bisection Method or Newton's Method.
    I thought this seemed weird to be in the pre-algebra and algebra section cause i am in calculus and solving this was beyond my knowledge
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  5. #5
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    yeh just looked at the question it says you need a graphics calculator to solve this one.
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  6. #6
    Senior Member I-Think's Avatar
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    On a random note, a few years of college will teach you how to use the Lambert W function to solve these equations.
    Lambert W function - Wikipedia, the free encyclopedia

    These types of questions always pop up on the forum once in a while. I'll give links when I have the time.
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  7. #7
    Senior Member I-Think's Avatar
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    Here's a link to a similar question that links to another similar question.

    http://www.mathhelpforum.com/math-he...nequality.html
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  8. #8
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    Re: Solving Exponential Equations

    Quote Originally Posted by Paymemoney View Post
    Can someone help me solve this equation
    e^x=x+2

    P.S
    ___________-x
    1 = (x + 2) e

    __
    -2___________-x-2
    -e__= - (x + 2) e____, where x >= -2

    _____________-2
    -x-2 = W-1( -e___)

    ______________-2
    x = -2 - W-1( -e___) (x >= -2)

    where W-1 is the negative branch of order -1 of Lambert's W function. Go to Lambert W function - Wikipedia, the free encyclopedia to find out how to compute this branch; you can use W-1(x) = ln(-x) - ln(-ln(-x)) or something more complex, depending on the accuracy required
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  9. #9
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    Re: Solving Exponential Equations

    This equation cannot be solved algebraically as it is trancedendal .
    you may use graphical methods or numerical ones.
    I enclose a graphical one the red line y=x+2 intercepts the blue curve y=e^x at two points...with their coordinates marked in the two figures below.

    Solving Exponential Equations-figure-001.png

    Solving Exponential Equations-figure-002.png
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  10. #10
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    Re: Solving Exponential Equations

    useless and childish
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