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Math Help - Solving Exponential Equations

  1. #1
    Newbie Auger's Avatar
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    Solving Exponential Equations

    Question is in the link. I just can't figure these 2 out.
    Thanks a lot....again!

    http://img9.imageshack.us/img9/7561/60225025.jpg (that exponent on the second equation is a -t)

    Auger
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  2. #2
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by Auger View Post
    Question is in the link. I just can't figure these 2 out.
    Thanks a lot....again!

    http://img9.imageshack.us/img9/7561/60225025.jpg (that exponent on the second equation is a -t)

    Auger
    (\frac{1}{32})^{4x} = 1024

    All these numbers are powers of two so it can be expressed as:

    \frac{1}{2^{20x}} = 2^{-20x} = 2^{10}

    If the bases are equal then the exponents must be equal: -20x = 10. Should be clear that x = -0.5

    -------------------

    \frac{20}{3+4e^{-t}} = 5

    Take the reciprocal of both sides and then multiply by 20

    3+4e^{-t} = 4

    Take 3 and then divide by 4:

    e^{-t} = \frac{1}{4}

    -t = -ln(4) = -2ln(2)

    t = 2\,ln2
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  3. #3
    Newbie Auger's Avatar
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    sorry i don't understand how you got to the second step. I have not learnt this. Could you explain?

    thanks
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