Let (x) = x 2 + x 1. (a) Show that the lines y = x

Let ƒ(x) = x² + x − 1.

(a) Show that the lines y = x + 3, y = x − 1, and y = x − 3 intersect the graph of ƒ in two, one, and zero points, respectively.
(b) Sketch the graph of f and the three lines from (a).
(c) Describe the relationship between the graph of ƒ and the lines y = x + c as c changes from −∞ to ∞.