Math 1 · Unit 3 · Lesson 6 · part 2 of 5
Two other forms, one main move
y = mx + b is the workhorse, and it stays the workhorse.
Two other forms, one main move
y = mx + b is the workhorse, and it stays the workhorse. But a line can be written in other ways, and you will meet two of them. The main move with either one is the same: rewrite it into y = mx + b so you can read m and b and graph it.
Standard form: Ax + By = C
The x term and the y term on one side, a plain number on the other. Example: 2x + 3y = 12.
Handy for one thing: finding both intercepts fast. Put x = 0 for the y-intercept, put y = 0 for the x-intercept.
Point-slope form: y − y1 = m(x − x1)
A shortcut when you know the slope m and one point (x1, y1). Example: slope 2 through (3, 5) is y − 5 = 2(x − 3).
It is Lesson 4's put-the-point-in move, written before you solve for b.
The main move. Whatever form you are handed, get y alone: y = mx + b. Then m and b do their two jobs and you graph as always: plot b, step by m.