Question

suppose f is a function whose domain is the set of real numbers, with f defined on this domain by the formula, f(x)= |x+6|

Explain why f is NOT a one-to-one function

Answer 1

Because f(0) = f(-12) = 6
function is only one-to-one if each x-value maps to a distinct and unique y_value

Answer 2

What dumbcow said. Just to prove that point, for example an x value of 4 and an x value of -16 both result in a y value of 10. So each x value does not map to a distinct and unique y value.