Math 1 · Unit 3 · Lesson 4 · part 2 of 6
Find m, find b, write it
Lesson 2 read m and b off an equation.
Find m, find b, write it
Lesson 2 read m and b off an equation. This lesson goes the other way from every starting point you might be handed. Whatever you are given, the job is the same: find m, find b, write y = mx + b. Say the plain English with each: m is the slope, the rate of change, rise over run; b is the y-intercept, the value when x is 0.
- 1From a graphRead b where the line crosses the y-axis. Count rise over run between two grid corners for m.
- 2From a tablem is the constant change in y per step of x. b is the y when x = 0. If the table does not show x = 0, walk the pattern back to it.
- 3From two pointsFind m first as rise over run. Then put one point into y = mx + b and solve for b (Unit 1 solving).
- 4From a slope and a pointYou already have m. Put the point in and solve for b.
Three of the four end the same way. Once you have m, you need b. Take any point you know, put its x and y into y = mx + b, and solve the one-step equation for b.