Final answer:
The slope of line segment DC cannot be determined without the specific coordinates. The slope of a line is a measure of its steepness, defined as the vertical change divided by the horizontal change between any two points on the line. For linear equations of the form y = mx + b, 'm' is the slope and 'b' is the y-intercept.
Step-by-step explanation:
To find the slope of line segment DC, you would need two points on the line segment (D and C) and their coordinates. If you know these coordinates, you can use the slope formula, which is (change in y)/(change in x) or (y2 - y1)/(x2 - x1). However, since the exact coordinates are not provided for points D and C, we cannot calculate the specific slope of line segment DC. Instead, let's explore how slope works generally, using the information from Figure A1.
According to Figure A1, the slope of a line is the ratio of the vertical change (rise) to the horizontal change (run) between any two points on the line. The slope is constant throughout the entire length of a straight line. For example, if a line has a slope of 3, as in the figure, this means there is a vertical rise of 3 units for every 1 unit of horizontal increase.
For a line represented by a linear equation such as y = mx + b, m represents the slope and b represents the y-intercept. Given that the y-intercept is where the line crosses the y-axis, figure A1 shows a y-intercept of 9. The slope is the m value of 3, meaning the line rises 3 units for every 1 unit it moves horizontally.
As for the practice test question regarding which equations are linear, options A, y = -3x, and B, y = 0.2 +0.74x, represent linear equations because they can be written in the form y = mx + b, where m and b are constants.