To determine if \( y = -x \) represents a proportional relationship, we need to check if \( y \) is directly proportional to \( x \). A proportional relationship can be expressed in the form \( y = kx \), where \( k \) is a constant.
In the equation \( y = -x \), we can identify that:
- The coefficient of \( x \) is \(-1\), which means \( k = -1 \).
Since \( k \) is a constant, \( y \) is indeed proportional to \( x \). Specifically, it is a linear relationship where \( y \) decreases as \( x \) increases, or vice versa. Thus, \( y = -x \) represents a proportional relationship.