Anatomy of a Line

Equation of a line

Interpretations of slope Used to describe the steepness, incline, or grade of a line. Measures the rate of change in y as x increases. … means that as x increases by 1 unit, y increases by slope (or -1.2 in this case)

Interpretations of y-intercept Indicates the y value at which the line goes through the vertical axis … means that when x is equal to 0, y is equal to the y-intercept (or 20 in this case).

What about units? Y-intercept is simply a measure of y, so it takes on the same units as y. In above example, the y units are in dollars, so we say that the y-intercept is $20. Slope is a RATIO of y to x (rise over run) so it’s units are equal to: In the above example we would say that the slope is $$ acres

Interpret: Slope – Equal to $1000/Sq Ft, or $107.7 per foot. In other words: if the size of a house increases by 1 square foot, we would expect the price to increase by $107.7 Y-intercept – doesn’t really make sense because it is negative, but equal to -$69,995.