Final answer:
When y is negative, x must be a negative number or zero in order for y to be negative.
Step-by-step explanation:
When y is a negative number, the value of x must be such that it results in a negative value for y. For example, if we have the equation y = -2x, any value of x that is positive will result in a negative value for y. So, x must be a negative number or zero in order for y to be negative.