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e^lnx question ?

Hi, i'm doing Core 3 Edexcel but am finding it quite tough. So i decided to look at some solomon worksheets from phyicsandmathstutor.com, as there are only so many past paper q's.

My question is how do you work out question 2 from this sheet:

https://4738aa85dc81f6cb672cd1f6a9985b3c87922ff3.googledrive.com/host/0B1ZiqBksUHNYVVdvc0h3MEZVb28/C3%20Exponentials%20and%20Logarithms%20A%20-%20Questions.pdf

It says do this without a calculator, but I'm not sure how to go about this. I know the answer to 2a is 4, but i don't know why. How do you go about doing the rest of Q2?

Also, do you think its worth looking at these worksheets or only doing exam q's? Feeling a bit overwhelmed about core 3 maths, and a little worried as I didn't do as well as i would have hoped in core 2 last year :s
Thanks for any help
Reply 1
Avatar for Vortex98
Vortex98
2
Since the natural log has base e, e^ln x is x . That being said, since x in 2a is 4, answer is 4. Try this approach for the rest. But, keep in mind that
1/2 ln x = ln (sqrt x)
1/3 ln x = ln(cuberoot x)
2ln x = ln (x^2)
yln x = ln (x^y)

These questions are good for skill building and strengthening concepts but I advise you to attempt harder questions too as the paper will never ask such direct questions
Reply 2
Avatar for Humiliation
Humiliation
OP
5
Original post by Vortex98
Since the natural log has base e, e^ln x is x . That being said, since x in 2a is 4, answer is 4. Try this approach for the rest. But, keep in mind that
1/2 ln x = ln (sqrt x)
1/3 ln x = ln(cuberoot x)
2ln x = ln (x^2)
yln x = ln (x^y)

These questions are good for skill building and strengthening concepts but I advise you to attempt harder questions too as the paper will never ask such direct questions


Thanks!

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