Final answer:
The line passing through (8, -3) and (-6, -3) is a horizontal line with a slope of 0, contrary to the misconception that the slope is undefined. Slope is undefined only for vertical lines.
Step-by-step explanation:
When analyzing the slope of a line that passes through two points, we rely on the formula for slope, which is defined as the change in the y-coordinate (rise) divided by the change in the x-coordinate (run). When a line is horizontal, like the one passing through (8, -3) and (-6, -3), there is no rise; hence the slope is 0, not undefined. The misconception about the slope being undefined is more appropriately applied to vertical lines, where the run is zero, leading to division by zero which is undefined. The information provided from Figure A1 also supports this by showing that a non-zero slope indicates a line that is either rising (positive slope) or falling (negative slope) as it moves along the x-axis. Since both points for our horizontal line have the same y-coordinate, we know that the line doesn't rise or fall, therefore its slope is zero.
Additionally, the m term in the equation of a line (y = mx + b) represents the slope, and the b term represents the y-intercept. In the context of a horizontal line, m would be 0 as the line is flat, and b would equal the constant y-coordinate of the line. The fact that this y-coordinate is negative in the question doesn't affect the slope; it would just place the y-intercept below the x-axis.
In summary, to clarify the original statement, the line passing through (8, -3) and (-6, -3) is indeed horizontal, and the correct slope is 0, indicating no rise or fall along the x-axis.