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# C3 Natural Logs Tweet

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1. C3 Natural Logs
I am trying to teach myself some of the C3 syllabus for when I go back to start year 13 on the 18th June but I got stuck on this question.

Make P the subject of:

Thanks,
Sora
2. Re: C3 Natural Logs
ln is the opposite of e^

3. Re: C3 Natural Logs
(Original post by Sora)
I am trying to teach myself some of the C3 syllabus for when I go back to start year 13 on the 18th June but I got stuck on this question.

Make P the subject of:

Thanks,
Sora
Remember,
4. Re: C3 Natural Logs
exponentiate both sides, so you get: Exp[LnP] = Exp[-.02t] becomes:

P = Exp[-.02t], since the exponential of a log of something is that something (because the function of an inverse of x is just x)
5. Re: C3 Natural Logs
P = 25e^(-0.02t)

I did what was suggested above and got the answer you gave, but then I went to check and saw this.
6. Re: C3 Natural Logs
(Original post by Sora)
P = 25e^(-0.02t)

I did what was suggested above and got the answer you gave, but then I went to check and saw this.
The book is wrong. The correct answer has been given by TenOfThem.
7. Re: C3 Natural Logs
(Original post by raheem94)
The book is wrong. The correct answer has been given by TenOfThem.
Thank you