A good bound that has been found for the logarithm (in a form that might be useful to you) is the following,
##\ln x \leq x^{\frac{1}{e}}##
That of course implies,
##|x \ln x| \leq |x^{\frac{e+1}{e}}|##
Now review the mathematical definition of ##f(x)=O(g(x))##. You'll get the answer for...