The Function Defined By $f ( x ) = x ^ { 2 } - 9$

Short Answer

The function defined by $f ( x ) = x ^ { 2 } - 9$ is/is not) a one-to-one function, whereas $g ( x ) = x ^ { 2 } - 9 ; x \geq 0$ 0 (is/is not) a one-to-one function.