Slope-intercept equation of a line (8th grade math/algebra 1)

In this first video, we learn that each line has an equation of the form y = mx + b which is the slope-intercept equation. In it, the "m" is the slope, and the "b" is the y-intercept. The line intersects the y-axis at the point (0, b).

Using our knowledge of slope as the "rise/run" and the y-intercept, we can now easily graph lines that are given in the slope-intercept form. The way to do that is: find the y-intercept point. Then use the slope and draw a 'rise-and-run' triangle to find another point on the line. Then draw the line using those two points.

In this second part, we first find the equations of two lines when their graphs are given. We can read both the y-intercepts and the slopes from the graph. Then we calculate the slope of a line going through two given points. The last example has to do with two painting services. We write equations for both, graph them, and consider the point where the lines meet.

See also

Slope — video lessons

Math Mammoth Grade 8 curriculum

Back to the list of 8th grade videos

Back to the index of all videos