Unit 5 Section 1 starts out by introducing t-charts and ordered pairs for displaying data points. A t-chart looks like a t with the two variables (x and y) on the top and numbers on the bottom. This t-chart shows some data points for the equation 2x = y.
This can also be shown with ordered pairs, for example (0,0) (1,2) (2,4). Both represent the same data and this data can then be plotted on a graph as shown above. An intercept is where the line crosses the x and y axis, in this case both the x and y intercepts are at (0,0). In any linear equation the x and y intercepts can be found by setting x or y to zero. If you set x to 0 and solve the result will be the y intercept, and if you set y to 0 and solve the result will be the x intercept of the line. Not all lines will have an x and y intercept, vertical lines will only cross the x axis and horizontal lines will only cross the y axis. Vertical lines will have equations that look like x=2 while horizontal lines will have equations that look like y=5.
Unit 5 Section 2 is about slope. Slope is how steep a line is and is calculated by rise/run, or the change in y divided by the change in x. Horizontal lines will always have a slope of 0 because the y value does not change and 0 divided by any number is still 0.