How do I find the range of this equation?

Question

y = x + 4/x

please explain

Answer 1

another way is to find the domain of the inverse function

y=x+4/x   x=0 is undefined

yx=x^2+4

x^2-yx+4=0

x=(y+-sqrt(y^2-16))/2

the argument of the sqrt must not be negative

y^2>=16

y<=-4 or y>=4   this is the range.