Straight lines
A line is y = ax + b: b is where it crosses the y axis, and a, the slope, is how much it rises per step right. Two points are enough: the slope is the rise over the run. Two lines with the same slope are parallel.
Where this sits
This is where the ladder starts: nothing is needed before it.
Exercises from this rung
Generated by the app, from easiest to hardest
What is the slope of the line through (0, 1) and (3, 4)?
- 2
- −1
- 1
- 3
Why From x = 0 to x = 3 the run is 3, and y goes from 1 to 4: 3 ÷ 3 = 1.
easierWhat is the slope of the line through (1, −5) and (3, −11)?
- −3
- 2
- 3
- −6
Why From x = 1 to x = 3 the run is 2, and y goes from −5 to −11: −6 ÷ 2 = −3.
in betweenWhich of these lines is parallel to y = x + 1?
- y = 2x + 2
- y = x + 2
- y = −x + 1
- y = x + 1
Why The slope of y = x + 1 is 1. The only one with the same slope is y = x + 2; only the y-intercept changes.
harder