can someone please help me with these 3 questions:

Question

1) Evaluate the limit.
lim_(x->infinity) (ln(ln(4 x)))/(4 x)

2)Find y ' and y ".
y= ln(5 x)/x^7

3)y =(arctan)(x - sqrt(1+x^2))

for this question i got y = -1/(2(1+x^2))which was wrong.

Please and thank you!