Final answer:
The equation x² is a non-linear relationship because it graphs as a parabola, not a straight line, and does not have a constant rate of change as a linear equation does.
Step-by-step explanation:
The equation x² represents a non-linear relationship. In mathematics, a linear relationship is one that, when graphed, results in a straight line, which can be described by an equation of the form y = mx + b or y = a + bx, where m (or b) is the slope and a is the y-intercept. The equation x² is a quadratic function, which will graph as a curved parabola and not a straight line. Therefore, it is not a linear relationship.
According to the provided Practice Test information, a linear equation is where there is a constant rate of change between the independent and dependent variables, represented by the equation y = b + mx. This doesn't apply to the equation x², which has a variable rate of change depending on the value of x. So, the correct answer to whether x² is linear is B) Non-linear relationship.