Mark M. answered 05/30/20
Retired math prof. Very extensive Precalculus tutoring experience.
I think that you mean limx→0 [(√(x+16) - 4) / x]. If so, this limit has the indeterminate form 0/0.
Multiply and divide by √(x+16) + 4 to get:
limx→0 [x / (x(√(x+16) + 4))] = limx→0 [1 / (√(x+16) + 4)] = 1 / 8