Log and Exponential questions (1 Viewer)

[renny 123]

1. If log8 3 = 0.528 find:

a) log8 2 b) Log8 6

2. Find the intergral from 0 to ln2 of: e^x/ e^x + 1

3. using the derivative of y= xlnx evaluate the integral from 1 to 2 of lnx dx

Help would be appreciated

 

[Herremann]

OK this is some assistance rather than giving you the answer. If you're still stumped post back.

1. a) You don't need to know log₈ 3 to work this out. You should be able to equate this quickly by solving 8^x = 2.
b) Use part a) and log₈ 3 = 0.528 to work this out.

2. This is just a standard ln integral question. As a hint, differentiate e^x + 1. This should clue you in to what you need to do.

3. Differentiating xln x using the product rule you get ln x +1. Now if you want to integrate ln x but all you can integrate is ln x +1, then why not integrate:
ln x +1 - 1
This is a fairly common trick where you alter what you want want into an expression that you can deal with that still equates to what you want.

Best of luck, hope these hints help.

Best Regards
Herremann