Answer:
Your friend is partially correct. The equation y = 4 represents a horizontal line at the constant value of 4 on the y-axis. However, to determine if your friend is entirely correct, we need more context. If this equation is meant to model a specific situation or relationship, it may or may not be accurate in that context. In terms of graphing, y = 4 is a valid equation, representing a horizontal line parallel to the x-axis at y = 4.