Hey, just a quick question regarding natural logarithms in questions in which the quotient rule is needed.
This is what I've done:
u = 1-lnx
v = x^2
du/dx = -1/x
dv/dx = 2x
Then when I expand everything (haven't cancelled anything out yet), I get:
However, the answer clearly says it's:
I don't understand how they got 2lnx when -2x multiplied by -lnx should give -2xlnx. If someone can help me here, I'll be very grateful. Thank you!
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Quick natural logarithms question! watch
- Thread Starter
- 12-10-2009 20:08
- 12-10-2009 20:09
There's a common factor of x on the top and bottom of your fraction. You've got the same answer effectively, but you haven't cancelled it down.
- 12-10-2009 20:12
I just did this question before. You've got to be doing OCR MEI right?
Oh and you take a common factor of the numerator. Like nuodai said.
- 12-10-2009 20:15