y = mx + b
Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 17 of 64.
One shape of equation hands over a line at a glance: y = mx + b, the slope-intercept form. The number multiplying x is the slope m; the lone number b is the y-intercept, the height where the line crosses the y-axis.
y = 2x + 1
reads: cross the y-axis at (0, 1), then climb 2 per step right. Nothing to compute; the equation is the drawing instructions.
Both readings can be checked against the rule itself: at x = 0 the mx term vanishes, leaving y = b, and each step of 1 in x adds exactly m to y. The form is popular because it wears its meaning openly.
Challenge
Draw the line y = 3x - 2 straight from its form.
Try it yourself
Draw the graph
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Graphs & Systems
1The Coordinate Plane
Two Numbers, One PointThe Four QuadrantsPoints on the AxesMirror PointsRecap: The Plane4Slope-Intercept Form
y = mx + bThe Starting HeightWrite the EquationSolve for yDraw From Any FormRecap: y = mx + b7Parallel & Perpendicular
Same Slope, Never MeetThe Perpendicular SlopeA Right-Angle LineRecap: Two Relations2From Rule to Line
A Rule Makes PointsThe Points Line UpOn the Line or Not?Between the DotsRecap: Rule to Line