How do you simplify this?

Question

-16^(1/4)

Someone showed me like this:
(-1)(16^(1/4))=(-1)(2)=-2

But others said ...
-16^(1/2)= 4i
4i^(1/2) or the sqrt of 4i=sqrt of 4 times sqrt of i
Final answer: 2 times sqrt of i

What is the correct answer and what exactly do you do??

Answer 1

Your first version is correct,
the "others" are wrong

To interpret along the second version it would have been

(-16)^(1/4) , but there were no brackets

just like in -2x^2 , it is only the x that is squared, not the -2

There is a major difference between
-2x^2 and (-2x)^2

that same major difference exists in your question

-16^(1/4) ---> -1 times the fourth root of 16 = -1(2) = -2
but
(-16)^(1/4)
= 2 √i , a messy complex number