The y-intercepts in the examples were described as convenient because they had values that were:

1. Whole-number coordinates are easier to read off a graph. 2. Slope needs two points that can be read accurately. 3. In the last two examples, the lines had y-intercepts with integer values. 4. That made the y-intercept convenient to use as one of the points. _Source: OpenStax Elementary Algebra 2e (CC BY 4.0), Ch 4 'Graphs', sections 4.1-4.7_