# Natural Logarithms help

#1
Hello,

I thought I understood natural logs but when this example came in apparently you were not allowed to work it out in this way. I remember that example coming up earlier but then forgetting about it.

(attachment below):

Why cant I take the natural logarithm and simplify like this, is there a specific rule I have to follow, can someone explain when and when I can not take natural logs like this because I thought you were able to , is it only when there is a single value next to the e like e^2x and you cant take it for e^2x+1. Why is this.

Help would be appreciated, thanks
Last edited by MicroMii; 1 month ago
0
1 month ago
#2
cannot find an attachment
0
#3
(Original post by the bear)
cannot find an attachment
it should be attached at the bottom, i will attach it here
0
1 month ago
#4
(Original post by MicroMii)
it should be attached at the bottom, i will attach it here
You can divide by 10 and you can take (natural) logs. However, the right hand side doesnt simplify as you might expect as
ln(a + b)
is not
ln(a) + ln(b)
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#5
(Original post by mqb2766)
You can divide by 10 and you can take (natural) logs. However, the right hand side doesnt simplify as you might expect as
ln(a + b)
is not
ln(a) + ln(b)
so would you have to do it a different way as if I was to take a ln there it would ahve to be ln (a+b)
0
1 month ago
#6
(Original post by MicroMii)
so would you have to do it a different way as if I was to take a ln there it would ahve to be ln (a+b)
What is the original question?

Half guessing the question / your writing, Id expect that the second one is T+5 (not T+s) so express the right hand side in terms of
e^(-T/8) * (...)
then rearrange/take logs to solve for T.
Last edited by mqb2766; 1 month ago
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