In Exercises 1-4,
(a) Use a graphing utility to graph the function and determine any x-intercepts of the graph and (b) Set y = 0 and solve the resulting equation to confirm your result in part(a).
1. y = 1 / x + 5 + 4 / x
2. y = 20(2 / x + 1 - 3 / x)
3. y = x - 6 / x - 1
4. y = x - 16 / x