## College Algebra (10th Edition)

RECALL: (1) The graph of the equation $x=h$ where $h$ is a real number is a vertical line whose x-intercept is $(h, 0)$. The slope of a vertical line is undefined. (2) The graph of the equation $y=k$ where $k$ is a real number is a horizontal line whose y-intercept is $(0, k)$. The slope of a horizontal line is zero. Thus, the missing expressions in the given statement are (in order): undefined; zero