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# C3 Natural Logs Help Watch

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1. 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
2. (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
3. you cannot say log( ex +ey ) is the same as logx + logy
4. (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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Updated: October 9, 2016
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