Problem with exponential question

Given that lnx =1.5 and ln√y =2.2 , evaluate

(i) http://latex.codecogs.com/gif.latex?...t%7By%7D%7D%29

(ii) 2x-y

The answer given is (i) 0.781 but i cant seem to get it.

For part (ii), im not sure how to even start.

Could somebody help me with this?

Thank you very much!

Re: Problem with exponential question

Quote:

Originally Posted by

**pumbaa213**

$\displaystyle \sqrt{\ln(ex)}=\sqrt{\ln(e)+\ln(x)}=\sqrt{2.5}$ Do you know why?

$\displaystyle \ln(y)=4.4$ Do you know why?

Re: Problem with exponential question

Okay i got the first part thanks alot! :) its so much easier when someone dissects it for you.

How about (ii) 2x - y

How should i start?

thank you!

Re: Problem with exponential question

You could start by putting x and y in simple terms. So:

$\displaystyle lnx=1.5 \textup{ so }x=e^{1.5}$

$\displaystyle ln\sqrt{y}=2.2$

$\displaystyle ln(y^{\frac{1}{2}})=2.2$

$\displaystyle \frac{1}{2}lny=2.2 \textup{ so }y=e^{4.4}$

Re: Problem with exponential question

yess! finally got the answer. Thank you plato and grillage! :)