Let us consider x^x^xupto infinity to be y
Then y=x^x^x^x...
It gives y=x^y. (Since x^x^x^...is y)
Then we can proceed
Take log on both sides
We get
Log y=logx^y
Logy=y logx
Now differentiate
d(logy)/dx=d(y logx)/dx
Now on RHS apply product rule.
We get
I/y*d(y)/dx=y/x+logx*d(y)/dx
Bring d(y)/dx on one side
Then take d(y)/dx common
Finally take the remaining part on other side you will get=
d(y)/dx=y^2/x(1-ylogx).