How Do You Know if Two Lines are Parallel?

Looking at these lines, you can see that they have the same steepness, or slope
The slope is the rise over the run, or how much y changes for a change in x
y=mx+b is slope-intercept form of a line, where m is the slope and b is the y-intercept
The slope of Line 1 is 2
The slope of Line 2 is also 2
Since the two lines have the same slope, they are parallel

1. In math the steepness of a line is called its SLOPE
2. So these two lines have the same slope
1. The RISE is how much the y-coordinate changes
2. The RUN is how much the x-coordinate changes
3. The slope is equal to the rise over the run
1. Since parallel lines have the same rise over run, and rise over run is the formula for slope, they have the same slope
1. If the lines have equal slopes, then they are parallel
1. Steepness is the same as slope
2. RISE over RUN is one formula for calculating slope
1. Slope-intercept form is y=mx+b, where m is the slope and b is the y-intercept
1. Slope-intercept form is y=mx+b, where m is the slope and b is the y-intercept
1. If our two lines have the same slope, that means they will be parallel
1. y=2x-2 is in slope-intercept form
2. The slope of this line is 2
3. You can tell this because in slope-intercept form, the slope is just the number in front of the x
1. Since parallel lines have the same slope, our second line must also have a slope of 2
1. As long as the slope is the same the lines will be parallel, no matter what the intercepts are
1. Line 2 has a slope of 2 and an intercept of 8
2. Since it has the same slope, 2, as Line 1, the two lines are parallel
1. Since the intercepts are different, they are different lines

Definition: Parallel Lines