3. When looking at a rational function f of x equals the quantity x minus six times the quantity x plus three times the quantity x plus four all divided by the quantity x plus six times the quantity x minus three times the quantity x minus four , Charles and Bobby have two different thoughts. Bobby says that the function is defined at x = −6, x = 3, and x = 4. Charles says that the function is undefined at those x values. Who is correct? Justify your reasoning.