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# Differentiating lnx watch

1. (Original post by Robbie242)
The x-coordinate is correct

Let me find the y-coordinate

when ,

Using log laws we have

so

I'm not sure about reasoning actually but working out the actual coordinate gives the answer the book has
are you rewriting ln(1/e) as two logs ln(1) - ln(e) ?
now sure how you get -1/e from that
2. (Original post by jacksonmeg)
are you rewriting ln(1/e) as two logs ln(1) - ln(e) ?
now sure how you get -1/e from that
Yeah
It's the division law

In this case we have

ln is the inverse of e so and (if you look at the graph)

so
3. (Original post by Robbie242)
Yeah
It's the division law

In this case we have

ln is the inverse of e so and (if you look at the graph)

so
we havent actually done section 3 in lesson. we jumped straight to differentiation and integration, not sure why. but none of it makes any sense, i guess ill start on the questions on section 3

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Updated: October 13, 2013
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