Three roots of the polynomial equation x ^ 4 - 4x ^ 3 - 2x ^ 2 + 12x + 9 = 0 are 3, - 1 and -1. Explain why the fourth root must be a real number. Find the fourth root.

Sample response: if the graph passes the horizontaline test, then the function is one to one. functions that are one to one have inverses that a therefore, the inverse is a hinction compare your response to the sample response above. what did you include in your explanation? a reference to the horizontal-line test d a statement that the function is one-to-one the conclusion that the inverse is a function done