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C3 Natural Logs Help

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    Hi,

    There are a couple of log questions that I'm stuck on:

    2e^x= 3e^-x +5
    2lne^x=3lne^-x +ln5
    2x= -3x + ln5
    5x= ln5
    x=0.32 I had a go but I feel like I'm following the wrong steps.

    The other one that I'm stuck on is:
    ln (2x+1) = lnx+2

    Thanks
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    (Original post by VioletPhillippo)
    Hi,

    There are a couple of log questions that I'm stuck on:

    2e^x= 3e^-x +5
    2lne^x=3lne^-x +ln5
    2x= -3x + ln5
    5x= ln5
    x=0.32 I had a go but I feel like I'm following the wrong steps.

    The other one that I'm stuck on is:
    ln (2x+1) = lnx+2

    Thanks
    Use brackets please. I'm not sure if it's 3e^(-x+5) or if it's 3e^(-x) +5
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    you cannot say log( ex +ey ) is the same as logx + logy
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    (Original post by VioletPhillippo)
    Hi,

    There are a couple of log questions that I'm stuck on:

    2e^x= 3e^-x +5
    2lne^x=3lne^-x +ln5
    2x= -3x + ln5
    5x= ln5
    x=0.32 I had a go but I feel like I'm following the wrong steps.

    The other one that I'm stuck on is:
    ln (2x+1) = lnx+2

    Thanks
    As thebear says, it is NOT true that ln(x + y) = ln x + ln y, so your first approach will get you nowhere!

    I would suggest multiplying both sides by e^x which will give you a quadratic in e^x.
 
 
 
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