15. Answer the following questions regarding the function
f(x)= x+5/x-1

(a) What is the domain of f?
(b) Is the point (2,6) on the graph off?
(c) If x = 3, what is f(x)? What point is on the graph of f?
(d) If f(x) = 9, what is x? What point is on the graph of f?
(e) If f a polynomial or rational function?​