S skyblue New member Joined Nov 5, 2006 Messages 13 Mar 8, 2007 #1 ln [radical ((x^2) + 4))] it is all under the radical. i did U'/U U'=2x U=(x^2) +4 so 2x / (x^2)+4 now is the answer: x / (x^2)+4 what happened to the 2 then from (2x)/(x^2)+4? can someone please help me. thank you.
ln [radical ((x^2) + 4))] it is all under the radical. i did U'/U U'=2x U=(x^2) +4 so 2x / (x^2)+4 now is the answer: x / (x^2)+4 what happened to the 2 then from (2x)/(x^2)+4? can someone please help me. thank you.
skeeter Elite Member Joined Dec 15, 2005 Messages 3,204 Mar 9, 2007 #2 \(\displaystyle \L y = \ln{\sqrt{x^2+4}}\) \(\displaystyle \L y = \ln{(x^2+4)^{\frac{1}{2}}}\) \(\displaystyle \L y = \frac{1}{2} \ln{(x^2 + 4)}\) \(\displaystyle \L y' = \frac{1}{2} \cdot \frac{2x}{x^2 + 4}\) \(\displaystyle \L y' = \frac{x}{x^2 + 4}\)
\(\displaystyle \L y = \ln{\sqrt{x^2+4}}\) \(\displaystyle \L y = \ln{(x^2+4)^{\frac{1}{2}}}\) \(\displaystyle \L y = \frac{1}{2} \ln{(x^2 + 4)}\) \(\displaystyle \L y' = \frac{1}{2} \cdot \frac{2x}{x^2 + 4}\) \(\displaystyle \L y' = \frac{x}{x^2 + 4}\)