Question #3168f

2 Answers
Nov 22, 2016

I don't believe you should've applyied L'H's rule since you would've been left with #oo^oo#.

Nov 22, 2016

No you cannot apply l'Hopital infinitely many times.

Explanation:

One problem with your approach is that the derivative of #x^x# cannot be found by the power rule. (It is not a power function.) We differentiate #x^x# by some version of logarithmic differentiation.

#x^x = e^(xlnx)#

so #d/dx (x^x ) = x^x(1+lnx)#

and the second derivative is

#d^2/dx^2 (x^x ) = x^x(1+lnx)^2+(x^x)/x#.