Answer:
Whichever line is straight and does not have x repeat itself is considered linear.
Step-by-step explanation:
A linear function can be shown by using the equation y=mx+b, in which m is the slope and b is the y-intercept. A linear function must be able to follow this formula in order to be considered linear. An exponential equation, quadratic equation, or other equation will not work.
Chances are, if the line is straight and the points plotted can be connected within a straight line and not overlap, they are a linear function.
[A function being an equation in which x does not repeat itself, therefore a vertical line up and down is not considered a linear function, however, a horizontal line is.]
