Chapter 4 - Exponential and Logarithmic Functions - Section 4.2 One-to-One Functions; Inverse Functions - 4.2 Assess Your Understanding - Page 291: 15

The function is not a one-to-one function.

For a function to be one-to-one, for each value of $x$, there must be a unique $y$ value paired with it and every element of the domain (D) must be paired with a unique element of the range (R). We notice that the domain elements with x-values $2$ and $-3$ are both paired with the same element of the range, $6$. This means that we have the same output for two different inputs. Therefore, the function is not a one-to-one function.