Two Numbers, One Point
Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 1 of 64.
Two number lines, crossed at zero, turn a pair of numbers into a place. The horizontal line is the x-axis, the vertical one the y-axis, and their crossing is the origin. A pair like (3, 2) is read in that order: 3 along the x-axis, then 2 up.
Three right, two up: the point (3, 2)
The order is the whole convention: (3, 2) and (2, 3) are different places. A negative first number goes left instead of right, a negative second number goes down instead of up, and (0, 0) is the origin itself, no steps at all.
Challenge
Place the points (4, 1) and (-2, 3) on the plane.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
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