Find f′(x)f'(x)f′(x) for f(x)=ln(x2+1)f(x) = \ln(\sqrt{x^2+1})f(x)=ln(x2+1).
x/(x2+1)x / (x^2+1)x/(x2+1)
1/(x2+1)1 / (x^2+1)1/(x2+1)
x/x2+1x / \sqrt{x^2+1}x/x2+1
None